Chapter 6.5, Problem 20PPS

To determine

To calculate the number of cupcakes Connie bought.

Answer to Problem 20PPS

2

Explanation of Solution

Given:

Cost of a cookie: $1

Cost of a cupcake: $3

Calculation:

Let the number of cookies be x and the number of cupcakes be y.

Connie buoyed 7 items for $15.

  $\Rightarrow x+y=\mathrm{7.................}(1)$

Cost of x cookie = $ x

Cost of y cupcakes = $ 3y

Connie spent $15 for 7 items.

  $\Rightarrow x+3y=\mathrm{15.............}(2)$

Subtract equation (1) from equation (2),

  $\begin{array}{l}\Rightarrow (x+3y)-(x+y)=15-7\\ \Rightarrow 4y=8\\ \Rightarrow y=2\end{array}$

Conclusion:

Therefore, the number of cupcakes that she bought is 2