tolong.... kasih tau caranya dong:)

1. 10/12+5/12= 15/12
2. 28/40-10/40=18/40
3. 7,6-3,9= 3,7+2,4= 6,1
4. 2/21
5. 13/6:1/3= 13/2

ralat no. 1 itu 10/12 + 5/12 = 15/12 = 1 3/12 = 1 1/4