Question 134301
{{{5x^2-80x=240-15x^2}}} Start with the given equation



{{{5x^2-80x-240+15x^2=0}}}  Subtract 240 from both sides.  Add 15x^2 to both sides. 



{{{20x^2-80x-240=0}}} Combine like terms



{{{20(x-6)(x+2)=0}}} Factor the left side 



Now set each factor equal to zero:

{{{x-6=0}}} or  {{{x+2=0}}} 


{{{x=6}}} or  {{{x=-2}}}    Now solve for x in each case





So our solutions are


 {{{x=6}}} or  {{{x=-2}}}