How Does a Climber's Mass Relate to Rope Stretch and Fall Distance?

[terrib]

A climber of mass m is scaling the vertical wall of a mountain. His safety rope is made of nylon that, when stretched, behaves like a sping with a spring constant k. He stops to rest, but then accidentally slips and falls freely for a distance h before the rope runs out of slack. The rope then stretches an amount x as it breaks his fall and momentarily brings him to rest. Derive an expression for the climbers mass, m, in terms of k, h, x, and g (the acceleration due to gravity).

When i think about this i automatically think to use the equation:

1/2(k)(y final^2) = (m)(g)(h initial)...
but I do not think that you can use two distances, it wouldn't make sense. Or is the y = to the height?

 

[rl.bhat]

The fall of potential = m*g*(h + x )
The energy stored in the spring = 1/2*k*x^2