Verified answer

A )

1 + 3/5 =   on réduit au dénominateur 5

5/5 + 3/5 = (5 + 3)/5 = 8/5

B)

2 - 2/7 =      dénominateur 7

 ( 2x7)/7 - 2/7 = 14/7 - 2/7 = (14 - 2)/7 = 12/7

C

- 5/4 + 8 /3 =                dénominateur 12

(-5 x 3)/(4 x 3) + (8 x 4)/(3 x 4) = -15/12 + 32/12 = (32 - 15)/12 = 17/12