So,
This is simply subtraction.
26.2 - 18.5 = 7.7 mi.
This is exact.
However, if you wanted to round to the nearest mile, it would look like this:
26 - 19 = 7 mi.
This is because in 26.2 mi., 2 is less than 5, and in 18.5 mi., 5 is greater than or equal to 5.
This is rounding to the nearest mile.
