How do you solve 8=r-5?

Oct 4, 2016

$\textcolor{g r e e n}{r = 13}$

Explanation:

Given
$\textcolor{w h i t e}{\text{XXX}} 8 = r - 5$

Remember that you can add the same amount to both sides of an equation and still maintain the validity of the equation.
$\textcolor{w h i t e}{\text{XXX}} 8 \textcolor{red}{+ 5} = r - 5 \textcolor{red}{+ 5}$
or
$\textcolor{w h i t e}{\text{XXX}} 13 = r$

Also remember that $b = a$ means $a = b$
So
$\textcolor{w h i t e}{\text{XXX}} 13 = r$ means $\textcolor{g r e e n}{r = 13}$