The perimeter of a rectangle is 90 inches. The length is 8 times the width. What is the length of the diagonal?

40

Step-by-step explanation:

The formula for the perimeter of a rectangle is P = 2l + 2w. Since the length is 8 times the width, l = 8w. You can plug this into the equation.

P = 2 (8w) + 2w

P = 16w + 2w

P = 18w

Now, plug in the given value for perimeter, and solve for w.

90 = 18w

(90) / 18 = (18w) / 18

5 = w

Since the width is equal to 5, you can now solve for l.

l = 8w

l = 8 (5)

l = 40

The length of the diagonal is equal to 40.