We can use the Pythagorean theorem to find the length of the short cut up the flight of stairs. The theorem states that in a right triangle, the square of the length of the hypotenuse (the longest side) is equal to the sum of the squares of the lengths of the other two sides.
Let's call the length of the short cut "x". Then, we can set up the following equation:
x^2 = 60^2 + 80^2
Expanding the squares:
x^2 = 3600 + 6400
x^2 = 10000
Taking the square root of both sides:
x = sqrt(10000)
x = 100
So, the length of the short cut up the flight of stairs is 100 meters.