If the 78.0 kg astronaut were in a spacecraft 6r from the center of the earth, what would the astronaut's weight be on earth?

The weight is mass (m) times gravity acceleration (g), weight = m*g

The mass given is 78.0 kg at the spacecraft and it is the same mass on earth (and on any place, given that the mass does not vary).

Then, if you take g = 9.8 m/s^2 on earth, weight = 78.0kg*9.8m/s^2 = 764.4 newtons.

764.4 N