Which one of the following is not a balanced equation

Ababy stroller is a rest on top of a hill which is 10 m high. the stroller and baby have a mass of 20 kg. what is the potential energy of the baby and stroller?

When you push downward on a book at rest on a table, you feel an upward force. does this force depend on friction? defend your answer.

Which describes increasing the efficiency of energy resource