Réponse :
A = 97/30; B = 34/21 ; C = 23/7; D = -14
Explications étape par étape :
A =-1x4/5x3 + 7/2 = -4/15+7/2 = (-4 x 2+7x15)/30 = (-8+105)/30 = 97/30
B = 7/3 + 3x-10/2x3x7 = 7/3 + -10/14 = (7x14+(-10x3))/3x14 = (98+(-30))/42 = 68/42=34/21
C = 13/7 + (-8/7) x (-5/4) = 13/7 + 40/28 = 13/7 + 10/7 = 23/7
D = (4x2-5x3)/2x3 ÷ (-2x4+3x3)/3x4 =(8-15)/6 ÷(-8+9)/12 = -7/6 ÷ 1/12 = -7/6 x 12/1 = -14
