The perimeter of a basketball court is
102 meters and the length is 6 meters longer than twice the width. what are the length and width?

P = 2(l + w) < perimeter of a rectangle

P = 102 meters
l = 6 + 2w
w = w

102 = 2[(6 + 2w) + w]
102 = 2(6 + 2w + w)
102 = 2(6 + 3w)
102 = 12 + 6w
102 - 12 = 6w
90 = 6w
90/6 = w
15 = w   or   w = 15

l = 6 + 2w
l = 6 + 2(15)
l = 6 + 30
l = 36

Check.
P = 2(l + w)
102 = 2(36 + 15)
102 = 2(51)
102 = 102

hope this helps and have a great day :)