pouvez vous maidez à faire ces exo please????!

bonjour

C = ( 8/3 - 2/5) : 7/5
c = ( 40/15 - 6/15) : 7/5
c = 34/15 x 5/7
c = 170/105
c = 34/21

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

1) vélo  + course = 3/4 + 1/5 = 15/20 + 4/20 = 19/20
nage = 1/20

1/20 = 100 m
20/20 = 2000 m

vélo = 2000 x 3/4 = 1 500 m
course = 2 000 /5 = 400 m