c’est pour demain s’il vous plaît j’ai du mal

Bonsoir,

a. 1 + 1/- 2 x 1/2

= 1 - 1/4

= (1 x 4) / (1 x 4) - 1/4

= 4/4 - 1/4

= 3/4

b. 5/9 x 27/4 + 5/6

= 135/36 + (5 x 6) / (6 x 6)

= 135/36 + 30/36

= 165/36

= (3 x 55) / (3 x 12)

= 55/12

c. 3/7 + 8/4 x (- 1/2)

= 3/7 - 8/8

= 3/7 - 1

= 3/7 - (1 x 7) / (1 x 7)

= 3/7 - 7/7

= - 4/7

d. - 7/15 x - 5/21 - - 4/3

= 35/315 + 4/3

= (35 x 1) / (35 x 9)

= 1/9

e. - 3 + 9/5 x 3

= - 3 + 24/5

= (- 3 x 5) / (1 x 5) + 24/5

= - 15/5 + 24/5

= 9/5

f. (3/15 - 3/20) x 5/9

= [(3 x 4) / (15 x 4) - (3 x 3) / (20 x 3)] x 5/9

= (12/60 - 9/60) x 5/9

= 3/60 x 5/9

= 15/540

= (15 x 1) / (15 x 36)

= 1/36.