# How do you take -4 + 3a^2 from 7a - a^2?

If you "take" $\left(- 4 + 3 {a}^{2}\right)$ from $\left(7 a - {a}^{2}\right)$ you get $\left(4 + 7 a - 4 {a}^{2}\right)$
To "take" A away from B, means to subtract A from B or, algebraically, $\left(B - A\right)$