Why does it not matter what letter or symbol is used to find an unknown number?

Identify the graph of y = ln x + 1.

Last month, a 770 g box of cereal was sold at a grocery store for $3.10. however, this month, the cereal manufacturer launched the same cereal in a 640 g box, which is being sold at $2.50. what is the percent change in the unit price?

On a piece of paper graft y+2> -3x-3 then determine which answer matches the graph you drew