Answer:
There are 8 nickels and 14 quarters.
Explanation:
Let n and q represent the numbers of nickels and quarters present.
Then q = n + 6 states that there are 6 more quarters than there are nickels.
($0.25)(q) + ($0.05)n = $3.90, in which we substitute n + 6 for q:
($0.25)(n + 6) + ($0.05)n = $3.90
Combining the n terms, we get 0.25n + 0.05n = 3.90 - 0.25*6, or:
0.30n = 3.90 - 1.50, or:
$2.40
n = ----------------------- = 8
0.30
There are 8 nickels and 14 quarters.
Check: 14 quarters comes to $3.50 and 8 nickels to $0.40, and $3.50 + $0.40 sums up to $3.90.