Answer:
b = 16
Explanation:
Since this is a right triangle, we can use the Pythagorean theorem
a^2 + b^2 = c^2 where a and b are the legs and c is the hypotenuse
12^2 + b^2 = 20^2
144+b^2 = 400
Subtract 144 from each side
b^2 = 400-144
b^2 = 256
Take the square root of each side
sqrt(b^2) = sqrt(256)
b = 16