Redundant question - the answer to that question is obvious from the first line of OP.how to solve a first order nonhomogeneous differential equation?
Deriving the differential equation is something and solving the differential equation is something else. The steps of the derivation of the differential equation is already written, but the steps of solving the differential equation to get the general solution is not written.of course i know this method but it is more complex and prolongs the derivation I'm asking for any less complex method to derive the equation