If a person weighs 240 pounds on Earth, what would be the difference in weight of the same person on Mars and on the Moon

Because weight = mass x surface gravity, multiplying your weight on Earth by the numbers above will give you your weight on the surface of each planet. If you weigh 150 pounds (68 kg.) on Earth, you would weigh 351 lbs. (159 kg.) on Jupiter, 57 lbs. (26 kg.) on Mars and a mere 9 lbs. (4 kg.)