Answer
45 inches
Work Step by Step
You are given the following:
$x$ = number of encyclopedias
$1.5x$ = total length of shelf needed in inches for $x$ encyclopedias
You are asked to find the length of shelf space needed for a set of 30 encyclopedias. Therefore, $x=30$.
Since you have an expression to find the length of shelf space needed for $x$ encyclopedias, and you know that $x=30$, plug that value into the expression:
$1.5(30)$
And solve:
$1.5\times30=45$
And remember to include your unit, which in this case is inches.
