les fractions b=8sur5-3sur4:9sur8 c=8sur3-2sur5le toutsur7sur5

bonjour

8/5 - 3/4 : 9/8
= 8/5 - 3/4 x 8/9
= 8/5 - 24/36
= 8/5 - 2/3
= 24/15 - 10/15 = 14/15

(8/3 - 2/5) : 7/5
= ( 40/15 - 6/15) : 7/5
= 34/15 x 7/5
= 238/75

b= (8/5)-((3/4)/(9/8)) = (8/5)-(2/3) = 14/15
c= ((8/3)- (2/5))/(7/5) = ((8/3)- (2/5))x(5/7) = (12/15)x(5/7) = 12/21