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.

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