bnsr quel qu'un peut m'aider svp. exercice 2et3

Ex2
45/63=(5x9)/(7x9)=5/7
357/561=(7x51)/(11x51)=7/11
1540/693=(20x77)/(9x77)=20/9
1080/1260=(9x180)/(7x180)=9/7

Ex3
A=(34/5)/(4/5-3/8)=(34/5)/(32/40-15/40)=(34/5)/(17/40)=34/5*40/17=34/17*40/5=2*8=16

B=7x10^4/2x(10³)²=3,5x10^(4-6)=3,5x10^(-2)=0,035

C=7/12-11/54*45/22=7/12-11/22*45/54=7/12-1/2*5/6=7/12-5/12=2/12=1/6