Respuesta :

12/3 = 4 30/3 =10% (4cupcakes is 10%)
4x10 = 40 10x10= 100 (40 cupcakes is 100%)
Rodeway
12 cupcakes ------------ 30%
x (cupcakes) ------------- 100% 

12 cupcakes ----------------- 0,3
x (cupcakes) --------------------- 1
0,3*x=12*1
0,3x=12    /:0,3
x= 12 : 0,3
x=40

She must make 40 cupcakes.