a) 10,5 +3 x (7 - 4) = 10.5 +3 x 3
= 10.5 + 9
= 19.5
b) 10,5 +3 x 7 - 4 = 10.5 + 21 -4
= 31.5 - 4
= 27.5
c) (10.5 + 3) x 7 - 4 = 13.5 x 7 - 4
= 94.5 - 4
= 90.5
d) ( 10.5 + 3) x (7 - 4) = 13.5 x 3
= 40.5
voila! en espérant t'avoir aidé :)