Question

A scale drawing uses the scale 3 in. = 20 ft. Find the missing measure.
____in = 26 2/3 ft

Answer 1

This is what we are told:
20 ft real measurement corresponds to 3 in. scale measurement (that's the given scale)
26 2/3 ft real measurement corresponds to unknown scale measurement
Let the unknown scale measurement be x
Now we wriite it as ratios:
20 ft : 3 in.
26 2/3 ft : x
Now we set the ratios equal to each other. That is a proportion.
20 ft : 3 in. = 26 2/3 ft = x
Change to fractions:
20/3 = (26 2/3)/x