If we let "N" equal the number of nickels and "Q" equal the number of quarters, we can create a system of equations that represents the total number of coins and the value of all coins:
N+Q=30
0.05N + 0.25Q = 3.30
If we solve the first equation for N --> N = 30-Q. Substituting this into the second equation:
0.05(30-Q) + 0.25Q = 3.30
1.50 - 0.05Q + 0.25Q = 3.30
0.20Q = 1.80
Q = 9
Substituting this into the maniupulated equation for N: N = 30-9 = 21
Therefore, there are 9 Quarters and 21 Nickels.
Doing a quick check: 0.05(21) + 0.25(9) = 1.05 + 2.25 = 3.30
