The two cars

Two cars $A$ and $B$ are in the vertex of two highways, forming an angle of $60°$ . The car $A$ goes straight at a constant velocity of $25 m/s$ . After $15$ seconds, the car $B$ starts at a constant acceleration of $4 m/s^2$ . Find the velocity (in $km/h$ ) in which the two cars separate after $25$ seconds the first car started.