ma puteti ajuta?la exercitiul 9 este urgent! multumesc

1+2/3=3/3+2/3=5/3
3-5/7=7/7-5/7=2/7
2+4/5=5/5+4/5=9/5
1-1/6=6/6-1/6=5/6
5+3/4=4/4+3/4=7/4
La ultima nu stiu scz