Efectue les opérations suivante 3+1/4=?? 9/7-64/63=?? 13/14+5/7=?? 3/4+5/24=??? 6/7-2/35=???

1) 13/4
2) 17/63
3) 23/14
4)23/24
5) 4/5

3 + 1/4 = 12/4 + 1/4 = 13/4
9/7 - 64/63 = 81/63 -64/63 = 17/63 
13/14 +5/7 = 13/14 +10/14 = 23/14
3/4 +5/24 = 18/24 +5/24 = 23/24
6/7 -2/35 = 30/35 -2/35 = 28/35 = 4/5