When a horizontal force P acts on a cart of mass 20 kg,it moves with a uniform velocity on a hofloor.When a force of 1.2P acts on the cart,it moves with an acceleration of 0.5m/s^2.Find the value of P

Since in first case body moves with a uniform velocity,the resultant force on it in the horizontal direction must be zero.
P + force of friction = 0
Force of friction= -P
In second case the,net horizontal force is (1.2P-P)=0.2P
Applying Newton’s second law,
F=ma
0.2P=20×0.5
5N