Hi there!
In order to answer your question you'll need to use the cross product method:
3 cups strawberries → 1 cup yogurt
2 cups strawberries → X cup yogurt
(1 × 2) ÷ 3 = X cup yogurt
2 ÷ 3 = X cup yogurt
X cup yogurt
Your answer is :
of a cup should be used if 2 cups of strawberries are used.
There you go! I really hope this helped, if there's anything just let me know! :)