Question

what is the total momentum of the bullet and the gun before the gun is fired?

Answer 1

M1u1+m2u2
where M is mass of the gun and m is the mass of the bullet

Answer 2

$\large\red{\pmb{\underline{\underline{\sf{Answer:-}}}}}$

⇒The total momentum of the bullet and the gun before firing would be zero because velocities of both of them will be zero.