This projectile has been thrown in an oblique movement, so it’s moving in x and in y at the same time. Vy varies due to gravity, and Vx is a constant as there is no gravity in the horizontal direction. In order to calculate Vx, you have to use the angle:
Vx=Vcosa=12m/scos(14.2)= 11.6m/s
So now you should use Vx the same way it is used in a uniform linear movement.
d=vt
dx=vxt
t=dx/vx=7m/(11.6m/s)=0.603s