We have:

Get everything on one side, starting with the highest power of x (for clarity). I added to the right hand side (it makes the working easier):

Every term on the right is divisible by 4. So I take this out as a "common factor" as such, by 'dividing' each term by the common factor, which is left outside the bracket:

There is also a common factor of as and . Again, out goes the common factor:

Which means that either , or

Can you finish up?

...And yes, when you've finished the year, you will look back over this and laugh at how simple it seems.