In[]:=
FullSimplify[DSolve[{D[u[x,t],t]+t^2D[u[x,t],x]==u[x,t],u[x,0]Exp[2x]},u,{x,t}]]
Out[]=
uFunction{x,t},
-
2
3
t
3
+
1/3

3
t

+2x

,uFunction{x,t},
-
2
3
t
3
-
1/3
(-1)
1/3

3
t

+2x

,uFunction{x,t},
-
2
3
t
3
+
2/3
(-1)
1/3

3
t

+2x

