Ответ:
Пошаговое объяснение:
#1
a) 3/8 * 5/7 = (3 * 5) / (8 * 7) = 15/56
b) 5/11 * 22/13 = (5 * 2) / 13 = 10/13
c) 2/25 * 15 = 30/25 = 6/5 = 1,2
d) 1 + (3/7) * 4 + (9/10) = 10/7 * 49/10 = 49/7 = 7
#2
a) 2/5 * (2/5 + 1/2) = 2/5 * (4/10 + 5/10) = 4/10 * 9/10 = 0,36 см2
b) S = 3/4 * 8 + 1/3 * 12 = 6 + 4 = 10км