If the shorter side is x feet, then the longer side will be x+14 feet. The perimeter will be the sum of all the sides and since this is a rectangle, the perimeter will be twice the sum of the shorter and longer side, thus:
2(x + x +14) = 264 feet. Divide both sides by 2:
x +x + 14 = 132, or:
2x + 14 =132. Now subtract 14 from both sides:
2x = 118. Divide both sides by 2:
x = 59 feet. The longer side is 14 feet more, and is therefore 59+14 = 73 feet.