Ответ:

Пошаговое объяснение:

289.

а) = 7/13 * 5/3 = 35/39

b) = -3/8 * 12/11 = -36/88 = -9/22

c) = -7/38 * 28/3 = -7/19 * 14/3 = -98/57 =

-1 41/57

d) = 7 * 22/15 = 154/15 = 10 4/15

290.

a) = 2/3 * 14/9 = 28/27 = 1 1/27

b) = 5/8 * (-21/20) = 1/8 * (-21/4) = -21/32

c) = -19/18 * 72/76 = -1/1 * 4/4 = -4/4 = -1

d) = 4/9 * 1/14 = 4/126 = 2/63