Weight of mass = w = m g = 5 * 10 Newtons
maximum amount of static friction force Fs = 0.4 * 5 * 10 = 20 Newtons.
If the applied force is less than 20 Newtons, the mass does not move. The amount of static friction force is equal to the applied force. Hence, it is equal to 10 Newtons.
If it is more than 20 newtons, then the mass moves and then the amount of friction will be the dynamic friction force = 0.3 * 50 N = 15 Newtons.