How Fast Was the Bullet Going Initially?

[dcangulo]

A 2.0 kg block of wood rests on a tabletop. A 7.0 kg bullet is shot straight up through a hole in the table beneath the block. The bullet lodges in the block, and the block flies 25 cm above the tabletop. How fast was the bullet going initially?

i tried using this formula:
p= [m$$_{}b$$/(m$$_{}w$$(sin90))]v$$_{}b$$

but it doesn't give me the velocity of anything
maybe I am using the wrong the formula for this?
does the 25cm play a part in anything??

 

[rl.bhat]

Using kinematic equation, find the initial velocity of block and bullet to reach a height 25 cm above table top. Then applying the conservation linear momentum find the velocity of the bullet.