If goal post is rectangle shaped then u can see distance of bc base is 3 times of its sides(distance from top to ground)(imagine aectangle) So let x be the distance so bc=3x Perimeter is given now u just put values in a formua of perimeter
This is a very basic area problem. You should try refreshing on some of your multiplication and addition skills. Try reading patterns, maybe. Also learning geometric proofs is VITAL.