This is what I calculated please tell me if its right or wrong.

Given: x^2+y^2=z^2, dz/dt=30ft/s, x=15, y=4

Unknown: z, dx/dt, dy/dt

x^2 + y^2 = z^2

15^2 + 4^2 = z^2

z = √241

To get the 30 ft/s, multiply sides of the triangle by 30/√241.

So, 15*30/√241 and 4*30/√241 => dx/dt = 450/√241 and dy/dt = 120/√241

So Chain rule: x^2 + y^2 = z^2 => 2x*dx/dt + 2y*dy/dt = 2z*dz/dt

2(15)*450/√241 + 2(4)120/√241 = 2(√241)30

13500/√241 + 960/√241 = 60/√241

=>60/√241 = 60/√241

So she's rising at a rate of 60√241 ft/s.