universal gravitation problem

Question

Tom has a mass of 87 kg. He and Sally are standing 37 m apart. What is Sally’s mass if the force of gravitational attraction between them is 5 x 10^-10 N?

Answer 1

F_g = G*M₁*M₂ / R²

Rearrange the equation to get M₂ = (R²*F_g) / (G*M₁)

M₂ = (37²)*(5x10^-10) / ((6.67x10^-11)*87) and plug that into your calculator (just to make sure you typed it in right, the answer should be between 100 and 120, but I want you to type it in yourself).