Question

Jude has seven times as many dimes as nickels their value is $5.25 how many nickels does he have.

Answer 1

1 nickel = $0.05
1 dime = $0.10

n - number of nickels
7n - number of dimes

A equation:
 
0.05n + 0.1 · 7n = 5.25
0.05n + 0.7n = 5.25
0.75n = 5.25          |divide both sides by 0.75
n = 7

Answer: He have 7 nickels.

Answer 2

Let dimes be represented by d and n for nickels;
1 dime= 0.1 dollars
1 nickel=0.05 dollars
0.1d+0.05n=5.25
d=7n
so,
0.1(7n)+0.05n=5.25
0.7n+0.05n=5.25
0.75n=5.25
n=7
There are 7 nickels and 49 dimes