Can someone help me solve number 33 with explanation please

Lifting a Chain In Exercises 33 and 34, consider a 15-foot hanging chain that weighs 3 pounds per foot. Find the work done in lifting the chain vertically to the indicated position. 33. Take the bottom of the chain and raise it to the 15-foot level, leaving the chain doubled and still hanging vertically (see figure). 6. 15 - 2y 3- X Answer + 168.75 ft-1b