№ 1. Выполните действие: а) 7/8 • 16/21; б) 1 8/25 • 1 4/11; в) 1 5/7 • 1 17/18; г) 5 • 3 7/15.

а) 7/8 * 16/21 = (7*16)/(8*21) = 112/168 = 2/3.
б) 1 8/25 * 1 4/11 = 33/25 * 15/11 = (33*15)/(25*11) = (3*5)/5 = 3.
в) 1 5/7 * 1 17/18 = 12/7 * 35/18 = (12*35)/(7*18) = (2*5)/3 = 10/3.
г) 5 * 3 7/15 = 5 * 52/15 = (5*52)/15 = 52/3.