Scientific notation is .a. used to keep track of very small and very large numbers during mathematical calculations b. used to accurately measure volumes used to measure length with precision c. used to communicate the level of precision

A. Used to keep track of very large and very small numbers during mathematical calculations.

Step-by-step explanation:

Some very large and small numbers are not easily represented in mathematical calculations. Using scientific notations help us to represent very large and small numbers to the power of 10.

The answer is C. 2x-70 and x+30 are congruent (equal in size) so 2x-70=x+30
then you find that x=100. So we solve 2(100)-70=130. We then solve for Y with 5y+130=180 Linear angles Paris always add to 180. We come out with Y=10