Exercice 25:
a.35/25=7x5/5x5=7/5
b.45/25=9x5/5x5=9/5
c.20/45=5x4/9x5=4/9
d.40/55=8x5/11x5=8/11
Exercice 26:
a.42/35=6x7/7x5=6/5
b.7/28=1x7/4x7=1/4
c.77/28=11x7/4/7=11/4
d.56/63=8x7/7x9=8/9
Exercice 27:
a.8/18=4x2/9x2=4/9
b.140/210=2x70/3x70=2/3
c.24/18=4x6/3x6=4/3
d.9/36=1x9/4x9=1/4
