Let

x = the number of cupcakes Nicolette frost

y = the number of cupcakes Evelyn frost

Nicolette frosts 3 cupcakes for every 2 that Evelyn frost means:

x : y = 3 : 2 cross multiply

2x = 3y

Together they must frost 160 cupcakes:

x + y = 160

We have the following system of equations:

2x = 3y

x + y = 160

........

click here to see the system of equations solved for x and y

........

x = 96 cupcakes

y = 64 cupcakes

Nicolette frost 96 cupcakes.

Evelyn frost 64 cupcakes.