First we will determine the type. Then general form of linear PDEs is

gives the type. Here so it's hyperbolic which means we can transform it to standard form, i.e. . After a change of variables and choosing our target form, we find that and must satisfy

or (choose one for and the other for ).

so satisfies and satisfies . Each are easily solved giving

from which we choose simple

Under this change of variables we obtain

This we can integrate twice.