Attraction and gravitational force.

Homework Statement

Two objects attract each other gravitationally with a force of 2.7 10-10 N when they are 0.25 m apart. Their total mass is 4.0 kg. Find their individual masses.
larger mass - I kind of guessed this was 4.0 kg but don't know how to do it.
smaller mass ? kg

The Attempt at a Solution

I don't quite understand how exactly this must be done. What formulas would i use?

Doc Al
Mentor
Use Newton's Law of Gravity. (No guessing allowed!)

Call the masses M1 and M2, if you like.

ahh.. i still dont get it???

Doc Al
Mentor
take two masses M1 and M2. problem says that M1+M2= 4.
Newton's law of gravitation says that force between two objects of mass M1 and M2 is

F = (gravitational constant) x (M1) x (M2) / (square of the distance)

so u know F, gravitational constant, the value of distance. Substitute these values in the above equation, u gonna get a relation beween M1 and M2 something like ,
M1= something times M2

substiute that in M1 + M2 = 4,