I need someone to check and go over my answers to make sure they are correct and if not could you go over them with my on why and how to solve correctly??

Question

Thank you much appreciated..

Add.

-4/5 + (9/20) = 5/25

1 + (-2) + 3 + (-4) = 10

5/3 + (-4/3) + 5/3 = 6/3

Answer 1

the last one is correct.
The first one, change to common denominator..

-16/20 + 9/20 = ?

The second, gather like terms...
4-6=?

Answer 2

first problem is = 1/5

second problem is = 2

and the third one is 6/2 would it be 6/3 or do I have to change it to 2? since 6 divided by 3 is 2?