Compare the expressions. 40 -16 plus 10 ? -20 plus 18 plus 30

What are the measures of ∠a, ∠b, ∠c and ∠d? explain how to find each of the angle measure.

To determine the number of deer in a forest a forest ranger tags 280 and releases them back

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?