Aider moi dm pour demain exercice 3,7 et 8

Exercice 3
a) 15/21=5/7
b) 18/27 = 6/9
c) -14/-28= -2/-4
d) -6/16 = -3/8
e) -3/15 = -1/5
f) 48/-36= 8/-6= 4/-2

Exercice 7
2/3+5/3 = 7/3
b) -4/7 +5/7 = 1/7
c) -3/8
d= -4/5
e) -5/9 - -7/9 = -5/9 +7/9 = 2/9
f) -9/2

Exercice 8
5/3 + 7/6 = 10/6 +7/6 = 17/6
b) -1/4 -8/12 = -3/12 -8/12 = -11/12
c) 4/15 +-7/3 = 4/15 +-35/15 = -31/15
d) 20/21 -6/7 = 20/21 -18/21 = 2/21
e) -7/8 -3/2 = -7/8 -12/8 = -19/8
f) 13/12 --5/6 = 13/12 + 10/12 = 23/12