Beginning Algebra With Applications, Chapter 2, 2.3, Section 2.3, Problem 88

Translate the phrase "four times the sum of a number and twenty" into a variable expression. Then simplify the expression.

$
\begin{equation}
\begin{aligned}
& \text{The unknown number: } n && \text{Assign a variable to one of the number quantities}\\
\\
& \text{The sum of the number and twenty: } n + 20 && \text{Use the assigned variable to write an expression for any other unknown quantity.}\\
\\
&= 4 (n + 20) && \text{Use the assigned variable to write the variable expression.}\\
\\
&= 4 (n) + 4(20)\\
\\
&= 4n + 80
\end{aligned}
\end{equation}
$