Gravity force between Earth and Moon from this angle

[Barooo50]

Homework Statement

Hello the text is in swedish but ill try my best to translate,
What it says is:
Determine the resultant force on the moon with regard to thr gravitation force from the sun and the Earth when it's in this position shown in the figure [ picture http://m.imgur.com/AfJOVZo ]
J represents Earth and M represents the moon, i hope you can help me! I will be very grateful if you do!

I tried 9.82 x 1/81 (moon weight to earth) but it was wrong!
It has to do with Newtons laws though (9.82 for Earth gravity force)

Homework Equations

The Attempt at a Solution

 

[Doc Al]

Hint: Look up Newton's law of universal gravity.

 

[siddharth23]

The Sun and Earth will exert separate gravitational forces on the moon. Try determining these forces first. Once you have them, you can use the concept of vector addition.