Can you please solve this problem for me? 49, a2, a3, 125/7

Subtract 8 1/6 - 4 5/6 . simplify the answer and write as a mixed number.

Divide. write in simplest form 41/6 divided by 10

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?