Explanation needed in one step in solving an equation

Question

Question is:

At a swim meet, Janet Dives from a diving board that is $40$ feet high. Her position above water is represented by the equation $h(t) = -16t^2 + 24t + 40$, where $t$ represents time in seconds and $h(t)$ represents height in feet?

And this is how they solved it. \begin{align*} 0 &= -16t^2 + 24t + 40\\ 0 &= 2t^2 - 3t - 5\\ 0 &= (2t - 5)(t + 1)\end{align*} I get that $0$ is plugged in, but how did they get from $16$ to $2$ in the next step?

Answer 1

Divide everything by $-8$. The equation $x=0$ is equivalent to $\frac{x}{-8}=0$.

Answer 2

Notice, the following steps $$0=-16t^2+24t+40$$ Taking $-8$ common from RHS we get $$0=-8(2t^2-3t-5)$$ since, $-8\neq 0$ hence dividing by $-8$ both the sides, we get $$\frac{0}{-8}=\frac{-8(2t^2-3t-5)}{-8}$$

$$0=2t^2-3t-5$$ $$0=\underbrace{2t^2-5t}+\underbrace{2t-5}$$ $$0=t(2t-5)+(2t-5)$$ $$0=(2t-5)(t+1)$$ That is the final result