What are the angle measures?

What could explain what happened when the time was equal to 120 minutes

Find the greatest common factor of the followig monomials 21u^5v,3u^4v^6, and 3u^2v^5

He mass of a single atom of carbon can be found by dividing the atomic mass (12.01 g) by 6.022 x 10^23. which is the mass of a single carbon atom, correctly written in scientific notation with the correct number of significant figures?