19 in = 1.6 ft
You know that
12 in = 1 ft
If you divide both sides by 12 in, you get the <em>conversion factor</em>: 1 = 1 ft/12 in.
If you divide both sides by 1 ft, you get the <em>conversion factor</em>: 12 in/1 ft = 1.
Both are conversion factors because they <em>both equal one</em> and <em>multiplying a measurement by one does not change its value</em>.
You choose the conversion that gives you the correct dimensions for your answer. It must have the correct dimensions <em>on top</em> (in the numerator),
Thus, to convert 19 in to ft, you use the conversion factor with “ft” on the top.
∴ Length = 19 in × (1 ft/12 in) = 1.6 ft