# How do you solve for r in p-r=r ?

##### 2 Answers
Mar 7, 2016

By adding r to both sides and dividing by two.

#### Explanation:

$p - r = r$, we must get all the r's on one side, so we can add the negative r on the left side to the positive r on the right.
$p = 2 r$, now in order to get r by itself, we must divide both sides by 2 which gives us our final answer.
$\frac{p}{2} = r$

Mar 7, 2016

$r = \frac{p}{2}$

#### Explanation:

We may do any operation on any side of an equation as long as we do the same operation on the other side as well in order to keep the equation true.

We thus perform operations such as to isolate the variable we are trying to solve for

So in this case, we first add $r$ to both sides and then divide both sides by 2.
This yields

$p - r = r$

$\therefore p - r + r = r + r$

$\therefore p = 2 r$

$\therefore \frac{p}{2} = \frac{2 r}{2}$

$\therefore \frac{p}{2} = r$