Labour efficiency variance

Good Day Sir

Please help with the following:

A company uses standard marginal costing. For April budgeted sales & production were 2000 units, actual ales & production were 2,200 units

Std selling price was $20 per unit, standard variable production cost was $14 per unit.

Actual selling price was $23 per unit, standard variable production cost was $15 per unit.

What was the favourable sales price variance?

My workings:

Actual: 2200×23=50,600
Std: 2200×20=44,000
Favourable price variance=6,600

But why don’t we take into account the production costs?

So would the efficiency variance then be:

Actual: 2,200x(23-15)=17,600
Std: 2,000(23-15)=16,000
=1600 favourable

OR
also as 200 @ $8=1,600 F?

Thanks
Zuzie