A force of 50.0 N is used to stretch an elastic so that it has 40.0 J of elastic potential energy. Assuming a perfect energy transformation, how much work was done in stretching the elastic? PLZZ HELP ASAP

I'm having some difficulty seeing the diagram clearly.but the question says there's a net inward force on the object.so we know right away,  from newton's 2nd law of motion, thatthat baby is accelerating.  it doesn't even matter which way thenet force is pointing.  if there's any net force, then either theobject's speed or else its direction must be changing.

Answerit decreases;