I wasn’t sure if the question was asking for a simplified expression or if it was asking for the x-value, so I solved for both (use whichever one you need.)
To simplify the expression, make sure to distribute the minus sign to the second part (so 5x^2 turns into -5x^2, 8x turns into -8x, and so on.) When you have that new expression, simply combine like terms.
To find X, just use the quadratic formula.
Hope this was helpful & accurate - let me know if you spot any errors or have any questions.