Solution
Step 1
Write the formula for the perimeter of a rectangle'
[tex]\begin{gathered} Perimeter\text{ of a rectangle = 2L + 2W} \\ L\text{ = length} \\ W\text{ = width} \end{gathered}[/tex]Step 2
Let then length = m
Width = m - 18
perimeter = 84m
Step 3
[tex]\begin{gathered} Perimeter\text{ = 2L + 2W} \\ 84\text{ = 2m + 2\lparen m - 18\rparen} \\ 84\text{ = 2m + 2m - 36} \\ 84\text{ + 36 = 4m} \\ 120\text{ = 4m} \\ \text{m = }\frac{120}{4} \\ \text{m = 30} \end{gathered}[/tex]Final answer
Length = 30m
Width = 12m
