0.6% of 36 = ? answer today this is due tomorrow! ,

Which statement is true for light passing into a medium that is more optically dense than the first medium through which it past

Will you chech and finish these for me, because i am stumped with them.

The two stars in a certain binary star system move in circular orbits. the first star, alpha, has an orbital speed of 36 km/s. the second star, beta, has an orbital speed of 12 km/s. the orbital period is 137 d. a) what is the mass of the star alpha? b) what is the mass of the star beta?