Question

Solve each equation. Check your solution.

$-7\left(p+8\right)=21$

Short answer

The required answer is $-11$.

Step-by-step solution

Step 1- Simplify left side of the equation

Use the distributive property $a\left(b+c\right)=ab+ac$ on left side the original equation.

$-7p-56=21$

Step 2- Isolate the variable p

Perform addition of 56 on both the sides of the equation.

$\begin{array}{c}-7p-56+56=21+56\\ -7p=77\end{array}$

Perform division of on both sides of the equation.

$\begin{array}{c}\frac{-7p}{-7}=\frac{77}{-7}\\ p=-11\end{array}$

– Check the obtained value 

Substitute the obtained value of p into the original equation and perform simplification for checking.

$\begin{array}{l}-7\left(-11+8\right)\stackrel{?}{=}21\\ -7\left(-3\right)\stackrel{?}{=}21\\ 21=21\end{array}$

Step 4- Make the conclusion

As the checking results in equal values on both the sides on substation of obtained value which means that obtained value is correct.