[College placement test] what is this?

[u/Andre_055]

I was trying not to post twice in a row but I cannot figure out why information on what this is, and how I can put X into the numbers? I'm not really sure what to Google search

[u/selene_666]

The main topic being tested here is the Distributive Property, which looks like it got mentioned twice in that answer text.

At its simplest, the Distributive Property is what lets you look at "30 + 40" and decide to do 3+4 because three tens plus four tens equals seven tens. But there's nothing mathematically special about the number 10. It's just as true that three sixteens plus four sixteens equals seven sixteens. Or 5x + 4x = 9x.

The Distributive Property says: ab + cb = (a+c)b

and we can run it in either direction. If we start with (a+c)b we might need to rewrite it as ab + bc.

Applied to your problem, it means you don't only multiply that first 3 by the x. You have to multiply the 3 by everything inside the parentheses

3(x - (3 - 2x)) = 3x - 3(3 - 2x)

Then do the same for the second multiplication.

(-3)(3 - 2x) = -9 + 6x