Answer: 12 inches
Explanation:
The 20 inches is the hypotenuse whereas 16 inches is the height of the triangle respectively.
So,
let keep the paper's length as x inches.
20² = 16² + x²
x² = 20² - 16²
x =

x = 12
I am not sure if this is right because i have never done a sum in inches before but I hope this helps sorry if it is not right.