You've just discovered a new X-ray binary, which we will call Hyp-X1 (Hyp for hypothetical). The system Hyp-X1 contains a bright, B2 main-sequence star orbiting an unseen companion. The separation of the stars is estimated abe 21 million kilometers, and the orbital period of the visible star is 3 days.

Use Newton's version of Kepler's thed law to calculate the sum of the masses of the two stars in the system. (Mint: Bee Mathematical Insight Measuring Stellar Masses in the book Give your answer in both kilograms and solar masses (MSur 1.10 10
Express your answer in kilograms to two significant figures.
_______