problems on solving rational equation

so i've been given a question :

5x / x-4 = 3x/2x + 7

and i had to solve for x, or the root u can say. I've gotten to the step where i cross multiply and bring everything to one side. And i got

7x^2 + 42 x, i'm not sure from here on how to solve for x or the roots.

i also have another rational problem like this :

x / x -2 = x^2-4x + 1/ x-3

and i have gotten to the step of bring everything to one side :

x^3 - 7x^2 + 12x -2 i'm not sure is this correct. but my teacher told me to solve with polynomial divison but i cannot find anything sets that polynomial to 0. so please help :S :D