The weight w of an object varies inversely as the square of the distance d from the center of the earth. at sea level (3978 mi from the center of the earth), an astronaut weighs 129129 lb. find her weight when she is 144144 mi above the surface of the earth and the spacecraft is not in motion.

with "k" being the "constant of variation"

so. hmm in this case is "w" inversely varying to the square of the distance or d²

thus   

solve for "k", to see what the constant of variation is

and plug it back in 

now.. .to find her weight when she's 144miles above the surface, well
that's just 

and since you already know what "k" is, just divide and simplify away, to get "w"