Answer: 8cm
Steps:
The formula for the perimeter of a rectangle is 2W+2L and the formula with your numbers put in is 2W + 2(5W). Because it's 2 times the width, and then then the length is 5 times the width.
The perimeter is "at most" 96. That means that perimeter ≤ 96.
Put all those values together
2W + 2(5W) ≤ 96
2W + 10W ≤ 96
12W ≤ 96 here we want to divide both sides by 12.
96 divided by 12 equal 8.
W ≤ 8 cm
The answer looks right!