Chapter SR24, Problem 7P

Solution

How many of each type of coin does Susan have?

8 coins of Dimes.

5 coins of Nickels.

Given:

Susan has 13 coins in her pocket with a total value of $1.05. She has only Dimes and Nickels.

Calculation:

According to questions -

Susan has coins in her pocket = 13

Total value of coins Susan have = $1.05

She has only Dimes and Nickels.

1 Dimes = $0.10

1 Nickels = $0.05

Let she have Dimes = x

And Nickels = y

Total coins = 13

  $x+y=13-----------equation1$

Total value of coins Susan have = $1.05

  $\begin{array}{c}0.10x+0.05y=1.05\\ 10x+5y=105\\ 2x+y=21----------equation2\end{array}$

Subtract equation 1 from equation 2-

  $\begin{array}{c}(2x+y)-(x+y)=21-13\\ 2x+y-x-y=21-13\\ x=8\end{array}$

As $\begin{array}{c}x+y=13\\ 8+y=13\\ y=13-8\\ y=5\end{array}$

So Susan has Dimes coins $x=8coins$

And Susan has Nickel coins $y=5coins$