help c'est pour demain :(

3/
a = 6/7 -3/5 = 30/35 -21/35 = 9/35

b = 3/4 x 2/15 = 6/60 = 1/10

c = 3/4 : 3/5 = 3/4 x 5/3 = 15/12 = 5/4

d = je n arrive pas a lire

4/
a = x/7 +3/5 = 5x/35 +21/35 = (5x+21) / 35

b = 7 +x/5 = 35/5 +x/5 = (35+x) /5

c = x/7 +x/2 = 2x/14 +7x/17 = 2x+7x /14 = 9x /14

d = x/2 +x = x/2 +2x/2 = 3x/2

5/

a = 1/3 +1/5 = 5/15+3/15 =8/15

b = 3/5 -5/3 = 9/15 -25/15 = -16/15

c =  1/3

d =  3/5