Réponse :
Explications étape par étape
Bonsoir
a.1÷2 + 7÷5
= 1/2 + 7/5
= 5/(2 x 5) + (7 x 2)/(5 x 2)
= 5/10 + 14/10
= 19/10
= 1,9
b. 8÷7 - 7÷12
= 8/7 - 7/12
= (8 x 12)/(7 x 12) - (7 x 7)/(7 x 12)
= 96/84 - 49/84
= 47/84
c.2÷23 - 11÷10
= 2/23 - 11/10
= (2 x 10)/(23 x 10) - (11 x 23)/(10 x 23)
= 20/230 - 253/230
= -233/230
d. -3÷4 - 7÷9
= -3/4 - 7/9
= -(3 x 9)/(4 x 9) - (7 x 4)/(9 x 4)
= -27/36 - 28/36
= -55/36
