Hi there!
Let's use x for the width because we know the width is only 1. Next, we'll use 5x for the length because the length is 5 times the width. Now, we can set up an equation to solve for x.
WORK:
x * 5x = 1620
5x^2 = 1620
x^2 = 324
x = 18
ANSWER:
The width of the rectangle is 18 centimeters
Hope this helps!! :)
If there's anything else that I can help you with, please let me know!