a lorry contains an engine with a power of 42,000w. how long will it take for the lorry to transfer 850j of energy

one person pulls 90n one way and the other has 100n pulling the other way.

so the net force = 90 - 100 = -10n,

or the ans can be 10n if the picture shows -90n and 100n instead.

answer///terminator or twilight zone;

the answer is c. the lower legs are levers, and the knees are fulcrums. the ankles hold the loads.