Which steps should be followed to use a scale drawing and a new scale to find the new length of a soccer field?

A. Add the numerator of the new scale to the old length to get the new length.

B. Subtract the new length from the old length to find the difference in lengths.

C. Write a proportion using the new scale as the first ratio. Set the first ratio equal to the ratio of the length of the original field compared to a variable that represents the new length of the field. Solve the proportion to find the new length of the field.

D. Write a ratio comparing the scale drawing length to the actual length of the field, and simplify.