The drawing (not to scale) shows one alignment of the sun, earth, and moon. The gravitational force vector F SM that the sun exerts on the moon is perpendicular to the force vector F EM that the earth exerts on the moon. The masses are: mass of sun = 1.99 x 10^30 kg, mass of earth = 5.98 x10^24 kg, mass of moon = 7.35 x 10^22 kg. The distances shown in the drawing are rSM = 1.5 x10^11 m and rEM = 3.85 x 10^8 m. Determine the magnitude of the net gravitational force on the moon.
Just use Newton's formula
F = GMm/d^2
to find the two forces on the moon.
Then add the vectors to get their resultant.
Post your work if you get stuck.