Bonjour besoin d aide svp Ex 2 Merci beaucoup

Bonjour,
Ex 2:
1) (9/5)-(7/5)×(2/11)
=(9/5)-(14/55)
=(9×11)/(5×11)-(14/55)
=(99/55)-(14/55)
=85/55
=(17×5)/(11×5)
=17/11

2) (4-3/2)/(14/9)
=(4-3/2)×(9/14)
=(8/2-3/2)×(9/14)
=(5/2)×(9/14)
=45/28

3) (3/4+2/7)/(9×(-1/2))
=(21/28+8/28)/(-9/2)
=(29/28)/(-9/2)
=(29/28)×(-2/9)
=(29/14)×(-1/9)
=(-29/126)