# For the formula D= [(v_i + v_f)/2] xx t, how do you solve for t?

Oct 17, 2015

$t = \frac{2 D}{{v}_{i} + {v}_{f}}$

#### Explanation:

You may perform any operation to any side of an equation, as long as you perform the same operation on the other side as well in order to keep the equation in balance.

Perform operations such as to isolate the variable you are trying to solve for.

So in this case, you can start by multiplying both sides of the equation by $2$ to get

$2 D = \left({v}_{i} + {v}_{f}\right) t$

Now divide both sides of the equation by $\left({v}_{i} + {v}_{f}\right)$ in order to isolate $t$. This yields :

$t = \frac{2 D}{{v}_{i} + {v}_{f}}$