The difference between city hall and the post office is 6 and 1/2 miles city hall is 1 and 1/4 miles closer to the library site than it is to the post office write an equation that represents the following statement: the distance from city hall to the library site plus the distance form the library site to the post office is equal to the distance from city hall to the post office

City hall to post office = 6 1/2 miles
City hall to library site = 1 1/4 miles
library site to post office = unknown. let it be x.    5 1/4 miles

1 1/4 miles + x = 6 1/2 miles
x = 6 1/2 miles - 1 1/4 miles

Find x.
1) convert the mixed fractions into fractions. 6 1/2 = 13/2 ; 1 1/4 = 5/4
x = 13/2 - 5/4
2) get the common denominator. 4 is twice as much as 2. multiply 13/2 by 2/2
13/2 * 2/2 = 26/4
3) Subtract the top numbers and put over the same denominator
x = 26/4 - 5/4 = (26-5) / 4 = 21 / 4
4) simplify the fraction
x = 21/4 = 5 1/4 miles from library site to post office.