A collection of nickels, dimes, and quarters amounts to $9.50. If there are 130 coins in all and there are twice as many dimes as there are quarters, find the number of nickels.

Answer 1

number of quarters --- x
number of dimes ----- 2x
number of nickels ----- 130 - x - 2x = 130-3x

5(130-3x) + 10(2x) + 25x = 950
650 - 15x + 20x + 25x = 950
30x = 300
x = 10
So there were 100 nickels

Check:

so 10 quarters --> $2.50
20 dimes and ---> $2.00
100 nickels -----> $5.00 -->total = $9.50