Bonjour,
a)
3 * ( 35/28 - 30/28) -3/8
= 3* -5/28 -3/8
-15/28 -3/8
= -15/28 * 8/8 - 3/8 * 28/28
= -120/224 - 84/224
= -204/224 = -102/112 = - 51/56
b)
(-4/2 + 1/2 ) * (2/4 -5/4)
= -3/2 * -3/4
= 9/6 = 3/2
