AP Physics B: Centripetal Force and Gravity

[stonecoldgen]

Homework Statement

Two stars of mass m₁ and m₂ are in orbit around their center of mass. If 2m₁=5m₂, and their orbital period is 120Ms, calculate the mass of the larger star, given that the distance between their centers is 1400Gm.

Homework Equations

F=GmM/r²

The Attempt at a Solution

I don't even know what to put as mass of the centripod, i kneed serious help

 

[ehild]

What have you learned about two-body problems? Reduced mass? Kepler's Laws?
ehild