subtract them, just like you added:
4x + 10 - (-5x +20)
The minus turns (-5x + 20) into the opposite, or 5x - 20
4x + 10 + 5x - 20
9x - 10
"Molly had (4x + 10) dollars. Ron has (-5x + 20) dollars. How much money do they have all together?"
For this part I got -x + 30 dollars, but the problem comes when I see the next part:
"How much more money does Molly have than Ron?"
Now how to I calculate that?
2 answers
-1x+30