Answer:
1: 7/10
2: 3/10
3: 4/8 (2/4 or 1/2 if you need to simplify it)
Explanation:
1: Convert 2/5 to tenths by multiplying the denominator and numerator by two. 3/10 plus 4/10 is 7/10
2: Convert 4/5 and 1/2 to tenths.
4/5 is going to be 8/10, 1/2 is going to be 5/10.
Subtract 5/10 from 8/10 to get 3/10
3: Convert 1/4 to eighths to get 2/8. Then add 2/8 and 2/8 to get 4/8.