Réponse + étape :
A= -2/3 + 1/6 = -2*2/3*2 + 1/6 = -4/6 + 1/6 = -3/6 = -1/2 = -0.5
B= 24/-15 * 40/36 = 24*40 / -15*36 = 960/-540= -16/9
C= 1/7 - 1/7 / 1/2 = 0 / 1/2 = 0
D= 6/5 *(1/2 + 1/3)
D= 6/5 * 1/2 + 6/5 * 1/3
D= 6/10 + 6/15
D= 6*1.5/10*1.5 + 6/15
D= 9/15 + 6/15
D=15/15 = 1