Answer:
20 Chocolate cupcakes and 15 vanilla cupcakes.
Explanation:
Use c for chocolate cupcakes and v for vanilla cupcakes.
3/4c=v
c+v=35
Use substitution
c+3/4c=35
1 3/4c=35 or 7/4c=35 --> Multiply by reciprocal
c=20
Plug it into an equation
20+v=35
v=15