1. Выполните действие: a) 7/8 * 16/21; b) 1/25 * 1 4/11; в) 5/17 * 17/18; г) 5 * 3/7 * 7/15.

a) 7/8 * 16/21 = (7 * 16) / (8 * 21) = 112 / 168 = 2/3; b) 1/25 * 1 4/11 = 1/25 * (15/11) = 15 / 275 = 3 / 55; в) 5/17 * 17/18 = (5 * 17) / (17 * 18) = 5/18; г) 5 * 3/7 * 7/15 = (5 * 3 * 7) / (7 * 15) = 15 / 15 = 1.