The width is 75.
Step-by-step explanation:
First you divide 324 by 2, because the formula is: 2(l + w)
324 ÷ 2 = 162.
Then I would subtract 162 by 87 because of the formula. (To find out width)
162 - 87 = 75
The width is 75.
You can double check by in-putting them into the above formula.
2(75 + 87) = 324