Explications étape par étape:

c) x = 5/7 - 7/3 = 15/21 - 49/21 = -34/21

d) -x = -2/9 - 1/3 = -2/9 - 3/9 = -5/9 x = 5/9

e) x = 9 ÷ 3 = 3

f) y = -3/5 = -0,6

g) z = -8÷-2 = 4

h) x = 0

i) z = 3/4 × 5 = 15/4

j) y = 1/3 ÷ 7/2 = 1/3 × 2/7 = 2/21