Answer:
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.
<em>P = 2(8w) + 2w</em>
<em>P = 16w + 2w</em>
P = 18w
Now, plug in the given value for perimeter, and solve for w.
<em>90 = 18w</em>
<em>(90)/18 = (18w)/18</em>
5 = w
Since the width is equal to 5, you can now solve for l.
<em>l = 8w</em>
<em>l = 8(5)</em>
l = 40
The length of the diagonal is equal to 40.
