Arc Length and Curvature (3D vectors)

Let *C* be the curve of intersection of the parabolic cylinder *x*2 = 2*y*, and the surface 3*z* = *xy*. Find the exact length of *C* from the origin to the point (5, 25/2, 125/6).

My instructor told us to put those equations in parametric form so we could use the arc length formula, but I am not sure how to put those in that form.

I know that these are the equations I must use, but how do I solve for t from the 2 equations I'm given??

x = x_o - at

y= y_o - bt

z = z_o - ct