I need help with parts d and e, thank you!

(13%) Problem 4: The Slingshot is a ride for two people. It consists of a single passenger cage, two towers, and two elastic bands. Potential energy is stored in the elastic bands and the passenger cage is released. On the way up, this potential energy in the elastic bands is converted into the kinetic energy of the cage. At the maximum height of the ride, the energy has been converted into gravitational potential energy of the cage. The slingshot has two towers of height h = 73 m. The towers are a distance d = 31 m apart. Each elastic band has an unstretched length of Lo = 41 m and a spring constant of k = 295 N/m. The total mass of the passengers and cage is m = 380 kg. The car is pulled down to the ground in the middle of the two towers. 20% Part (a) Write an expression for the stretched length L of one of the elastic bands strung from the cage to the top of its tower. ( h 2 + ( d/2) 2 ) 1/2 - Correct !