Measure height of apartment building

Building height is measured from finished grade located within 2 feet of the foundation wall to the highest point on the building or structure. ... The building height is the vertical distance between finished grade and the highest point on the building, provided that the measured elevation does not include fill or berms.

if a = 1,   and b = 2, then the answer is 47.99999999. if you round that to the nearest whole number, the answer is 48.

so, converting firstly the mixed fractions to improper fractions and then "adding".