Question

7. Lee has $10.20 in a jar that contains only nickels

Answer 1

There are 76 nickels in jar

Solution:

Let "d" be the number of dimes

Let "n" be the number of quarters

1 dime = $ 0.10

1 nickel = $ 0.05

There are 140 coins in the jar

Therefore,

d + n = 140

n = 140 - d ------- eqn 1

Lee has $10.20 in a jar that contains only nickels  and dimes

Therefore,

$d \times 0.10 + n \times 0.05 = 10.20$

0.1d + 0.05n = 10.20 -------- eqn 2

Substitute eqn 1 in eqn 2

0.1d + 0.05( 140 - d) = 10.20

0.1d + 7 - 0.05d = 10.20

0.05d = 3.2

Divide both sides by 0.05

d = 64

Substitute d = 64 in eqn 1

n = 140 - 64

n = 76

Thus there are 76 nickels in jar