Biology 20 help i'm so confused!!!?

Question

A caterpillar worth 200J of energy is consumed by another animal. If the caterpillar passes 100J of it's energy to f***s, 70J to cellular respiration, and 30J to tissue growth, how much of the caterpillar's potential energy available to the next trophic level is not transferred? (please show your work or explain how you get your answer cuz i've tried over and over and i can't make any sense out of it)

Answer 1

Of the 200J consumed 30J is passed on to the next level and 170J is used (70J ) or lost (100J).

Thus 170/200 x100 =85% is not tranferred giving a transfer of 30/200 x 100 =15%.