Answer:
12 nickels and 9 dimes
Step-by-step explanation:
1/ We have: n + d = 21 <=> d = 21 - n or opposite (n = 21 - d)
2/ We have: 0.05n + 0.10d = 1.50 and then we will put 1/ into 2/
=> 0.05n + 0.10(21 - n) = 1.50
=> 0.05n + 2.1 - 0.1n = 1.5
=> -0.05n = -0.6
=> n = 12
Nevertheless, d = 21 - n = 21 - 12 = 9
