It's pitch, the number of inches of rise for each 12 inches of run.
A "3 in 12" roof rises 3 inches for every 12 inches of run.
a. What is the slope of a "3 in 12" roof?
ratio 1: 12
1/ 12 = 3/ x
x= 36
b. A roof rises 100 inches over a run of 20 feet. Find the slope of the roof.