Answer:
70.0 kg
Step-by-step explanation:
The mass of a person (a measure of the amount of matter in a person) does not change on going from Earth to Mars.
The person's mass on Mars would be 70.0 kg.
However, the weight of a person (the gravitational attraction of Earth or Mars for the person) does change.
A person who weighs 687 N on Earth would weigh 229 N on Mars.