2y + x = 50
x = 50 - 2y
y = (50 - x) / 2
z = 25

z^2 + y^2 = x^2

y = (50 - x) / 2
y = (50 - (50 - 2y)) / 2
y = (50 - 50 + 2y) / 2
2y = 50 - 50 + 2y
y = y

x^2 = 625 + y^2

y = 18.75