Variance analysis question

Hi dear,

Q1. The budgeted contribution HMF Co. for June was $290,000. The following variances occurred during the month.
                        
Fixed overhead expenditure variance $6,475 F
Total direct labor variance $11323 F
Total variable overhead. Variance $21,665 A
Selling price variance $21,875 F
Fixed overhead volume variance $12,500 A
Wales volume variance 36,250 A
Total direct materials variance $6,335 A
What was the actual contribution for the month?

The answer is:
Standard marginal costing reconciliation

Original budgeted contribution $290,000
Sales volume variance ( $36,250)
==========================
Sales contribution from actual sales $353,750
Selling price variance               $21,875
===========================
                                              $275,625

variable cost variances
Total direct material variance.  ( $6,335)
Total direct labour variance.      $11,323
Total variable overhead variance ($21,665)
===========================
Actual contribution.                 $ 258,948

My question is : as my knowledge we should calculate only the variances which comparing between actual and budgeted, as it required by what they give us in question,

So why we used also the other variances?

Q2. A company uses a standard absorption costing system. The following figures are available for the last accounting period in which actual profit was $108,000.
Sales volume profit variance $6,000 A
Sales price variance $5,000 F
Total variable cost variance $7,000 A
Fixed cost expenditure variance $3,000 F
Fixed cost volume variance $2,000 A

What was the standard profit for actual sales in the last accounting period?
The answer is:$109,000

                                                              $
Budgeted profit.                       not required
Sales volume variance            not needed
Standard profit on actual            109,000.   
Sales price variance                    5,000 F
Total variable cost variance        7,000 A
Fixed cost expenditure variance 3,000 F
Fixed cost volume variance         2,000 A
Actual profit                                    108,000

Why we don’t need the sales volume variance?
& we calculate the variances of Fixed cost volume and expenditure variances despite of they are comparing between actual and budgeted  not standard cost per unit at actual units.?

Q3. A company uses standard marginal costing. It’s budgeted contribution for the last month was $30,000. The actual contribution for the month was $20,000, and the following variances have been calculated :
~Sales volume contribution variance $5,000 A.
~Sales price variance $10,000 F.
~Fixed overhead expenditure variance $30,000 F.

What was the total variable cost variance?
The answer is: $15,000 A

The total variance between budgeted contribution and actual contribution is $10,000 A ( $30,000_ $20,000). The sales volume and sales price variances sum to $5,000 F, so to balance, the variable cost variance must be $15,000 A.

Explain for me please why we did not used in our calculation fixed overhead expenditure variance, but in other questions we did.? What is the logic?

Q4. Crystal Co uses a standard absorption costing system.. The following figures are available for the last accounting period, for which standard profit was $135,000.
                                                           $
Sales volume variance.                 15,000A
Sales price variance.                      10,000F
Total variable cost variance.         7,500A
Fixed cost expenditure variance. 5,500F
Fixed cost volume variance.         4,000A

What was the actual profit for the period?

The answer is.: $139,500

A profit adjustment for the difference between budgeted and actual volumes is not required, and so the sales volume variance should be ignored.
$135,000_ $4,000 +$5,500 _ $7,500 +10,500=$ 139,500.

My question is, why sales volume is not uses in our calculation but the fixed cost and volume variances is uses in our calculation, as the three variances above is comparing actual and budgeted?

22.14 Q5. A company uses a standard absorption costing system. Last month budgeted production was 8,000 units and the standard fixed production overhead cost was $15 per unit. Actual production last month was 8,500 units and the actual fixed production overhead cost was $17 per unit.

What was the total adverse fixed production overhead variance for last month?

The answer is $17,000.                              $
8,500 units should have cost (×$15).    127,000
but did cost (8,500 ×$17).                        144,500
                                                                     =17,000 A

My question is in fixed OH variance we compare the actual with the budgeted
But here they are comparing the actual cost with
standard cost per unit for actual units produced. Why is that?

Thanks.