I need a lot of help

To add fractions with different denominators you must find the highest common factor (the highest number they both go into).
For 1 - The highest common factor is 8, 2x4 = 8, 4x2 = 8
now, whatever you do to the bottom, you must do to the top.
So:
3 x 2 = 6 and 5 x 4 = 20
Therefore, your answer would be 6/8 + 20/8
You do that for the rest of them as well, do you get it?
Answer:
3. 4/15 + 4/5 = 4/15 + 12/15 = (4+12)/15 = 16/15
5. 2/3 + 7/10 = 20/30 + 21/30 = (20+21)/30 = 41/30