Пошаговое объяснение:
8*1/7 + 3*1/9 = 8/7 + 3/9 = 8/7 + 1/3 = 24/21 + 7/21 = 31/21 = 1 10/21,
32*1/48 + 21*1/14 = 32/48 + 21/14 = 2/3 + 3/2 = 4/6 + 9/6 = 13/6 = 2 1/6,
3/5*15 + 18*2/3 = 3 * 3 + 6 * 2 = 9 + 12 = 21
ответ:21
