Hi i'm having trouble using the multivariable chain rule on this question thanks!

Consider the hyperbolic paraboloid z = a2 - y2. A drone is programmed to fly along the surface of the hyperbolic paraboloid. The flight instruments measure the velocity in the x, y and z directions as dx = 2 dy = 3 dz = 1 . dt dt dt The GPS measures * = 30 , but the GPS does not measure y (to keep costs down). What is the y co-ordinate? The chain rule can tell us! It's y = Number