One way to approach the problem is to use conservation of energy. Part of the gravitational potential energy is converted to kinetic energy. Given the directions, we can assume conversation of energy.
The energy converted is the change in height multiplied by gravity multiplied by the mass. That same amount of energy will become kinetic energy.
So you can set that amount of energy equal to the equation for kinetic energy and solve for the velocity.
You could also use the kinematic equations. The initial velocity would be zero.