A slingshot consists of a light leather cup containing a stone. The cup is pulled back against two parallel rubber bands. It takes a force of 15 N to stretch either one of these bands 1.0 cm. (a) What is the potential energy stored in the two bands together when a 54-g stone is placed in the cup and pulled back 0.11 m from the equilibrium position? (b).With.what speed does the stone leave the slingshot? Enter a number.