A gearbox gives a 5 to 1 reduction. With 100 pound-feet of input torque, the output torque is about

Correct answer to question 80 (Mechanical Comprehension): 500 pound-feet

Method

A reduction multiplies torque by the same factor it divides speed, so 100 x 5 = 500 pound-feet while the output shaft turns a fifth as fast. Answering 20 divides where it should multiply.