fairly easy high school physics problem (Work and Energy)??

Well the work is the ratio between Force over distance while energy has two equations (i think.haha i forgot the other one)
Potential Energy= mass*gravity*height
Kinetic Energy=1/2*mass*velocity.

I hope that would help!

The basic argument is to apply the work-energy theorem:  The work done on a mass by the net force acting on it changes the mass's kinetic energy by that same amount.

What you need to do is first find the work done on the arrow (use the definition of work as force times the distance through which it acts).  Then equate that to the change in the arrow's kinetic energy.  (Since the arrow starts from rest it starts out with zero KE, which makes things easier.)

You should be able to find the arrow's speed once you know the value of its kinetic energy.

ADDED-
I feel I should point out a couple of errors in the first answer above.  Work is force *times* distance, not force over distance.  And kinetic energy is 1/2 *mass*speed^2.  That's speed *squared*.