Knowing that an inch is equal to 40 miles you can take 40 and multiply it by 2 1/4, thus getting 90. Or, you can break it down. 2 times 40 equals 80. This leaves 1/4 inch left to figure out. If you divide 40 by 4 (figuring out a fourth) you would get 10. Add 80 and 10 and you would have 90 miles.
