rotation speed help?

Question

Suppose a star the size of our Sun, but of mass 8.0 times as great, was rotating at a speed of 1.0 revolution every 20 days. If it were to undergo gravitational collapse to a neutron star of radius 20 km, losing three quarters of its mass in the process, what would its rotation speed be? Assume that the star is a uniform sphere at all times and that the lost mass carries off no angular momentum.
in rev/day?

I asked this question previously, but did not understand the response given to it......it ended with finding the mass of the star when I obviously need the rotation speed.....anyways, could someone help?

Answer 1

Angular momentum is a conserved quantity.