Math
posted by Josh .
Dave has quarters, dimes and nickles in his bank. He has 3 more dimes than quarters and 6 less nickles than quarters. There are 63 total coins. How many are quarters?

I used guess and check until I got it. Sometimes you have to take the time to do this.
q 17, d 20, n 11 = 48
q 20, d 23, n 14 = 57
q 23, d 26, n 17 = 66
q 22, d 25, n 16 = 63
The last one works. 22 quarters, 25 dimes, and 16 nickels. 
x Qtrs
(x + 3) dimes
(x  6) nickles
x + (x + 3) + (x  6) = 63
3x  3 = 63
x = 22 Qtrs.