What was the rocket's speed

A rocket fires a projectile at a speed of 0.97 c while traveling past the earth. An earthbound scientist measures the projectile's speed to be 0.81 c.
v = _______________________c


thanks. i think 'c' means the speed of light

V = (V1 + V2)/(1 + V1 V2/c²)

0.97c = (V1 + 0.81c)/(1 + 0.81c * V1/c²)

V2 = 0.747 c