Bonjour :)
A = 8/7 × x = 16/63
x= 16/63 ÷ 8/7
x= 2/9
donc : 8/7 × 2/9 = 16/63
B = -5 × 4/x = y/9
y= -5 × 4 = - 20
x= 9 ( car 1 × 9 = 9 )
donc : -5 × 4/9 = - 20/9
Bon courage !
