Bonjour,
a)1/6+3/6
= 4/6
= (2 x 2) / (2 x 3)
= 1/3
b)31/14-5/14
= 26/14
= (2 x 13) / (2 x 7)
= 13/7
c)25/33+19/33
= 44/33
= (11 x 4) / (11 x 3)
= 4/3
d)15/37+22/37
= 37/37
= 1
e)45/143+20/143
= 65/143
= (13 x 5) / (13 x 11)
= 5/11
f)1/27+4/27+7/27
= 12/27
= (3 x 4) / (3 x 9)
= 4/9
g)16/28-7/28-7/5-/28 --> Il manque un nombre