lhs = sympify("e*x +f")`
rhs = sympify("g*y + t*x +h")`
eq = Eq(lhs,rhs)
e*x + f == g*y + h + t*x

IsolateVariablesToLHS(eq,[x,y]) # desired function
(e-t)*x - g*y == h-f # now x and y are on LHS and remaining are on RHS