Answer:
Cost of French silk cheesecake = $11.95
Cost of chocolate marble cheesecake = $18.51
Explanation:
Let the cost of French silk cheesecake = x
and the cost of chocolate marble cheesecake = y.
From the directions given, we have the below equations in x and y

Multiply equation (2) with 11 and subtract from (1)

Cost of French silk cheesecake = $11.95
Cost of chocolate marble cheesecake = $18.51