The weight of an object on the moon is 1/6 of its weight on Earth. If a moon rock weighs

20 1/2 lb on Earth, how much did the rock weigh on the moon?

1/6 = 0.16 = 16%

restate the question: 16% of 20.5 is what?

multiply: 20.5*.16 = 3.28

now, to find the weight of the object on the moon, subtract 16% from 20.5. 16% of 20.5 is 3.28

20.5 - 3.28 = 17.22 = 17 22/100 = 17 11/50

the weight of the object is 17 11/50 pounds on the moon.