Bonjour,
A = − 2/5 / 3 15 + 2 /15
− 2/ 5 / 3 15 = (-2*15) / ( 5*3) =
-30/ 15
-30/15 + 2/15 = -28/15
B = 4/5 × 1 /4 + 2/ 5
4/5 × 1 /4 =4/20 = 2/10
2/10+ 2/15 = 30/150 + 20/150 = 50/150 = 5/15 = 1/3
C = (1/3 − 4/3 )× 2/ 5
1/3 - 4/13 = -3/3 = -1
-1*2/5 = -2/5