I have never learned this in school, I only learned algebra when you have $x$ and numbers, in equations, like this:
$$2x = 5(-2 + 5x)^2$$
I can solve that, but I cannot solve this one:
$$-3(7 -2x)^2 -5(1 + x)^2$$
How can I solve this one?
On the book, answer is: $$-17x^2 +74x -152$$