Question 173320
Let the base be {{{x}}}, then the height is {{{x+6}}}


Since the area is given by {{{A=bh/2}}}, you can just substitute:


{{{13.5=(x(x+6))/2}}}


Distribute, collect like terms, and put the equation into standard form for a quadratic:


{{{27=x^2+6x}}}


{{{x^2+6x-27=0}}}


Solve this by factoring, recognizing that {{{-3*9=-27}}} and {{{-3+9=6}}}.


One of your roots will be a negative value.  Exclude that root because it is extraneous introduced by the act of squaring the variable.  The other root will be the length of the base.