# algebra

posted by
**sonya**
.

(2a+4b)-(3a-b)when and how do u know to change the signs?

It might help to think of it as below.

(2a+4b)-1(3a-b)

Mutliply the last term by the -1.

2a+4b-3a+b = -a+5b or 5b-a

I hope this helps. Thanks for asking.