ACT Practice Question: Isolating Variables

 
Here is an ACT math practice question on rearrangement of algebraic expressions and isolating the relevant variable.

In the equation $s = \dfrac{1}{2}(u+v)t$, $s$ is the distance traveled by an object in time $t$ with an initial velocity of $u$ and a final velocity equal to $v$. Which of the following solves this formula for $v$ ?

1. $\quad \dfrac{2su}{t}$
2. $\quad \dfrac{2s-u}{t}$
3. $\quad \dfrac{2s-ut}{t}$
4. $\quad \dfrac{2s-t}{u}$
5. $\quad 2s – ut$