Using the pythagorean theorem (a^2 + b^2 = c^2), this would make the equation 48^2 + b^2 = 80^2 (the hypotenuse must be plugged in as the "c" value).
Once you solve, this becomes 2304 + b^2 = 6400.
Subtract 2304 from 6400 and you get b^2 = 4096.
Take the square root of 4096 and you get b=64.
The answer is 64.
