l=3w+5
2(3w+5)+2w=250 (both w and l have to be multiplied by two because there are two sides)
This can be simplified to: 6w+10+2w=250
Now subtract 10 from both sides and add the two w's together.
This makes: 8w=260
Divide both by 8: 32.5-w=32.5
32.5 times 2=65
250-65=185, divided by 2=92.5
Length=92.5
Width=32.5
hope this helped!