Janet spent 30% of her money on 7 cupcakes and 4 cookies on Monday. The cost of each cupcake was twice the cost of each cookies. She bought some more cupcakes and another 10 cookies with 6/7 of her remaining money on Tuesday. How many cupcakes did she buy on Tuesday?

Guest May 28, 2021

#1**+1 **

Janet spent 30% of her money on 7 cupcakes and 4 cookies on Monday. The cost of each cupcake was twice the cost of each cookies. She bought some more cupcakes and another 10 cookies with 6/7 of her remaining money on Tuesday. How many cupcakes did she buy on Tuesday?

Let the amount she started with = A

Let the cost of a cookie = C and the cost of a cupcake = 2C

So

.30A = 4C + 7(2C) ⇒ .30A = 18C ⇒ A = (18C) / .30 = 60C

So she had .70A left after spending .30A and 6/7 of this = (6/7) .70A = .60A = .60(60) C = 36C

So with this the amount she spent on cupcakes on Tuesday =

36C - 10C = 26C = 13 (2C)

So...she bought 13 cupcakes

CPhill May 28, 2021