2 feet and 1 in. Explanation is subtract 3’8 from 6’4 then add 9in too it. Feet can only go to 12in. But you’ll get 3’4. Then add 9 and you’ll get 3’13 so you’ll get 4’1 and then just subtract that from 6’4 and you get 2’1
If 0.25 in on a drawing is 12 ft in real life, than 1 in on the drawing is 48 ft in real life.
Just divide 15 by 48
15/48=0.3125
So the length of 15 in real life to a drawing is 0.3125 inches.