Let y represent number of miles between the two cities and x represent number of cm between both cities.
We have been given that on a map of North Carolina, 27 centimeters represents 18 miles. We are asked to determine the equation that would calculate the number of miles between the two cities, y, when they measure x centimeters apart.
We will use proportions to solve our given problem.

Upon substituting our given values in above equation, we will get:


Now we will multiply both sides by x.


Therefore, our required equation would be
and 1st option is correct choice.