Question 26116
Your reasoning is correct, but your formula is not. The perimeter of a rectangle is is 2*(l+w), so the correct formula is:

2*(x+(x+60))=520
2*(2x+60)=520
divide by 2;
(2x+60)=260
subtract 60,
2x=200
divide by two,
x=100=width
length is 60+x=160
The area is l*w=100*160=16000