Look at the largest triangle. Its hypotenuse is 10, its shortest side is x, and its longer leg is sqrt(80). Apply the Pythagorean Theorem to calculate x. Square sqrt(80); result is 80. Square 10; result is 100. Square x; result is x^2.
Then, by the Pyth. Thm, 80 + x^2 = 100. Solve first for x^2, and then take the positive square root of the result, to obtain the leg length of the largest triangle.
Think: Would the Pyth. Thm. help you find y and/or z?