Answer
4
Work Step by Step
Evaluate $\frac{a-b}{3}$ when a is 3 times b and a=18.
Given the value of a, find b.
$a=3b\longrightarrow$ Substitute for a.
$18=3b\longrightarrow$ Divide both sides by 3.
$18\div3=3b\div3\longrightarrow$ Solve.
$6=b$
Substitute for a and b in the original equation.
$\frac{a-b}{3}=\frac{18-6}{3}=\frac{12}{3}=4$
