Collision in mid air!

In the figure shown, the two projectiles are fired simultaneously. If the initial speed of the left projectile for the two projectiles to collide in the mid-air is $n\sqrt{\frac{2}{3}}$ m/s, then find the value of 'n'.

Clarification: The initial speed of right projectile is $20$ m/s and the angles made by both projectiles with the horizontal are shown in figure. Distance between both the projectiles initially is $10$ m.