Bullet Mass & Speed: Impact on Block Motion

[alwysnforevr002]

A bullet with a mass of 6.00 g is fired through a 1.25 kg block of wood on a frictionless surface. The initial speed of the bullet is 896 m/s, and the speed of the bullet after it exits the block is 435 m/s. At what speed does the block move after the bullet passes through it?

For this one i thought that i would find the average velocity first but i can't do that without knowing the distance it traveled so i went back to square one.

 

[neutrino]

Square one says conservation of momentum.