Answer:
1. 7/10 + 10/100
= 7/10 + 1/10
= 7+1/10
= 8/10
= 4/5
2. 50/100 + 4/10
= 1/2 + 4/10
= 5/10 + 4/10
= 5+4/10
= 9/10
3. 9/10 + 10
= 9/10 + 100/10
= 9+100/10
= 109/10
4. 1/10 + 40/100
= 1/10 + 4/10
= 1+4/10
= 5/10
= 1/2
5. 70/100 + 2/10
= 7/10 + 2/10
= 7+2/10
= 9/10