Question

Joanna has a total of 7 rolls of coins worth $23. She has rolls of dimes worth $5 each, and

rolls of nickels worth $2 each.
How many rolls of each kind does she have?
4 rolls of dimes and 3 rolls of nickels
2 rolls of dimes and 5 rolls of nickels
5 rolls of dimes and 2 rolls of nickels
3 rolls of dimes and 4 rolls of nickels​

Answer 1

3 rolls of dimes and 4 rolls of nickels

Explanation:

Number of rolls of dimes = x

Number of rolls of nickels = y

Total number of rolls = 7

x + y = 7 -------------------(i)

Total amount = $ 23

5x + 2y = 23 ----------------(ii)

Multiply equation (i) by -2. So when we are adding, y will be eliminated and you will get the number of rolls of dimes.

(i)*(-2) -2x - 2y = -14

(ii) 5x + 2y = 23 {Now add}

3x = 9

x = 9/3

x = 3

Plug in the value of x in equation (i)

3 +y = 7

y = 7- 3

y = 4