# How do you solve 7x + 30=51?

Apr 22, 2018

$x = 3$

#### Explanation:

Take away the constant…

$7 x + \cancel{30} - \cancel{30} = 51 - 30$

$7 x = 21$

Divide by $7$ to find $x$:

$x = \frac{21}{7} = 3$

You can check by using the equation:

$\left(7 \times 3\right) + 30 = 21 + 30 = 51$ which is correct.

Apr 22, 2018

$x = 3$

#### Explanation:

$\text{isolate 7x by subtracting 30 from both sides of the }$
$\text{equation}$

$7 x \cancel{+ 30} \cancel{- 30} = 51 - 30$

$\Rightarrow 7 x = 21$

$\text{divide both sides by 7}$

$\frac{\cancel{7} x}{\cancel{7}} = \frac{21}{7}$

$\Rightarrow x = 3 \text{ is the solution}$

$\textcolor{b l u e}{\text{As a check}}$

$\left(7 \times 3\right) + 30 = 21 + 30 = 51 = \text{right side}$