Question

John has four more nickels than dimes in his pocket, for a total of

$1.25. Which equation could be used to determine the number of
dimes, x, in his pocket?
(1) 0.10(x + 4) + 0.05(x) = $1.25
(2) 0.05(x + 4) + 0.10(x) = $1.25
(3) 0.10(4x) + 0.05(x) = $1.25
(4) 0.05(4x) + 0.10(x) = $1.25

Answer 1

The correct equation would be: 2.) 0.05(x+4) + 0.10x = $1.25

A nickel is worth 5 cents. A dime is worth 10 cents.

no. of nickels = x + 4
no. of dimes = x

nickels + dimes = 1.25
0.05(x + 4) + 0.10x = 1.25
0.05x + 0.20 + 0.10x = 1.25
0.15x = 1.25 - 0.20
0.15x = 1.05
0.15x/ 0.15 = 1.05 / 0.15
x = 7 *no. of dimes.

no. of nickels = x + 4 = 7 + 4 = 11

To check:
0.05(11) + 0.10(7) = 1.25
0.55 + 0.70 = 1.25
1.25 = 1.25