First you need to use the formula for perimeter.
Then translate the statement: 10 times the length equals 17 times the width
Then solve that equation for L.
L=(17/10)W (divided 10 on both sides)
Now you know: P=216 L=17/10W and W=W
Replace P, L, and W into the perimeter formula
P= 2L +2W
216 = 2((17/10)W) + 2W
Now solve for W.
216 = (34/10) W + 2W ———-> 17/5W + 10/5W
216 = 27/5 W ————-> (5/27)216= 27/5W (5/27)
Plug in W=40 to find L
I will let you finish the problem. I hope this helped you get started.