Bonsoir,
13/60 + 52/55
On cherche un dénominateur commun : 60 x 11 = 55 x 12 = 660
= (13 x 11)/(60 x 11) + (52 x 12)/(55 x 12)
= 143/660 + 624/660
= (143 + 624)/660
= 767/660
19/20 - 5/44
Un dénominateur commun est 220 car 20 x 11 = 44 x 5 = 220
= (19 x 11)/(20 x 11) - (5 x 5)/(44 x 5)
= 209/220 - 25/220
= 184/220
On peut simplifier :
= (46 x 4)/(55 x 4)
= 46/55
15/17 - 13/16
= (15 x 16)/(17 x 16) - (13 x 17)/(16 x 17)
= 240/272 - 221/272
= 19/272
