Chad built a scale model of a statue. he built the model 7 inches tall to represent the actual height (a), in feet, and the height of model (m), in inches?

The correct question in the attached figure

Let
a---------> actual height in feet
m-------> height of model in inches

we know that
scale=15 ft/7 in------> equation 1
scale=a/m--------> equation 2
equals 1 and 2
15/7=a/m
clear variable a
a=m*(15/7)

clear variable m
m=a*(7/15)

therefore 

the answer is 
the option B  m=a*(7/15)