answer?

What grade are you in? I don't understand your math, I hav an idea but it'll probably be wrong.

Give it a go Coldplay and I will tell you whether or not you got it right,

Then i can teach 2 of you at once :)

Hint:  Be careful with the minus sign.

think of it like this

5a+3b        +       -4(2a-5)     -8a