What is the total cost of a sweatshirt if the regular price is 42 dollars and the sales tax is 5 1/2

Need solving this second acceleration problem.

Find the area of the regular hexagon if a side is 20 cm.

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?