Bonjour,
a)
x= 4/3 + 5/4 = 16/12 + 15/12 = 31/12
b)
x= 5/7 -7/3 = 15/21 - 49/21 = -34/21
c)
x= 3/12 +5/8 = 6/24 +15/24 = 21/24 = 7/8
d)
1/3 + 2/9 = x
x= 1/3 +2/9 = 3/9 + 2/9 = 5/9
e)
5/18 -11/45 = x
x= 5/18 -11/45 = 25/90 - 22/90 = 3/90 = 1/30
f)
x= -11/15 + 12/25 = -110/ 150 + 72/150 = -38/150 = - 19/75
