Awater-balloon launcher with mass 4 kg fires a 0.5 kg balloon with a velocity of 3 m/s to the east. what is the recoil velocity of the launcher?

I think we will use the law of conservation of linear momentum;
M1V1 = M2V2
M1 =  4 kg (mass of the water balloon launcher)
V1=?
M2= 0.5 kg ( mass of the balloon)
V2 = 3 m/s

Therefore; 4 V1 = 0.5 × 3
                   4V1= 1.5
                     V1= 1.5/4
                          = 0.375 m/s