Answer:
9 nickels
Explanation:
He doesn't have that many coins, and there are 4 choices, so let's use the guess method.
Try 7 nickels.
7 * $0.05 = $0.35
16 - 7 = 9
9 * $0.25 = $2.25
The quarters alone are worth more than $2.20, so this is not the answer. We need more nickels and fewer quarters.
Try 11 nickels.
11 * $0.05 = $0.55
16 - 11 = 5
5 * $0.25 = $1.25
$0.55 + $1.25 = $1.80
The coins are worth too little. We need fewer nickels and more quarters.
Try 9 nickels.
9 * $0.05 = $0.45
16 - 9 = 7
7 * $0.25 = $1.75
$0.45 + $1.75 = $2.20
The coins are worth the correct amount.
Answer: 9 nickels