Okay so what number when dividing, goes in the inside and outside; -0.27 divided by -0.9

Write a real-world word problem that can be solved by adding 34.99 and 5.79. then solve

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?

3x + 4y = 5 x- 3y = -7 solve by substitution