Question

Given that the mass of the Milky Way galaxy is 10^11 times that of the Sun and that the sun is 2.6x10^20 meters from its center, what is the Sun's orbital speed around the center of the galaxy? How long does it take the Sun to orbit the Milky Way? (In this problem, we assume that the galaxy can be treated as a single, spherical blob of matter. Strictly speaking, this isnt correct, but the far more elaborate math needed to calculate the problem properly ends up giving almost the same answer)