Earth attracts a person with a gravitational force of 7.0 × 102 newtons. what is the magnitude of the force with which the individual attracts earth?

Gravity always acts as a pair of equal, opposite forces.

Your weight on Earth is the same as the Earth's weight on you.

The person in the question attracts the Earth with a gravitational
force of  700 newtons.

This person likes to go skydiving on the weekend. 

When he jumps out of the airplane, there's a force of 700 newtons
pulling him down toward the Earth, and there's a force of 700 newtons
pulling the Earth up toward him.

The force of 700 newtons pulling him down toward the Earth accelerates him
downward at the rate of 9.8 m/s².  That's the rate of gravitational acceleration
due to Earth's mass when an object is about 3,900 miles from its center.

The force of 700 newtons pulling the Earth up toward him accelerates the Earth
upward at a smaller rate.  That's the rate of gravitational acceleration due to his
mass when an object is centered about 3,900 miles from him.