Solve the linear equation
n/2 - 3n/4 + 5m/6 = 21
L.C.M. of the denominators, 2, 4, and 6, is 12.
Multiplying both sides by 12, we obtain 6n − 9n + 10n = 252
⇒ 7n = 252
⇒ n = 252/7
⇒ n = 36
