1 inch = 15 miles: Franklin to Washington is 45 Miles (3 inches) Franklin to Lincoln is 30 miles (2 inches) How much farther from Franklin is Washington than is Lincoln?

I worked it out to be 7 1/2 miles but my teacher says I am wrong? She says the answer is either 11 - 17 - 14 or 28 miles?? How can this be? Could someone help me with this? Thank You

I don't get one of those answers either.

45 - 30 = 15