variance analysis

W Ltd uses a standard marginal costing system. The following data relates to one of its products.

selling price: $ 27/unit
variable cost:$12/unit
fixed cost :$9/unit
profit :$6/unit

Budgeted sales for control period 7 were 2400 units, but actual sales were 2550 units.The revenue earned from these sales were $67320.

Profit reconciliation statements are drawn up using marginal costing system. Whar sales variance would be included in such a statement for period 7?

A. price variance: $1530(A) volume variance: $900(F)
B. price variance: $1530(A) volume variance:$2250(F)
C. price variance: $1530(A) volume variance: $2250(A)
D. price variance: $1530(F) volume variance : $2250(F)

The correct answer is B

I have been able to calculate volume variance by (2550-2400) x (27-12)= $2250(F)

however I did not been able to calculate price variance

I would be grateful if you can help me sir.