Question 546819
What you've done so far is good!
Now you need to solve the resulting quadratic equation for x (the width).
{{{x^2+6x-300 = 0}}} Use the quadratic formula: {{{x = (b+-sqrt(b^2-4ac))/2a}}} where: a = 1, b = 6, and c = -300.
{{{x = 9-6+-sqrt(6^2-4(1)(-300))/2(1)}}} which evaluates to:
{{{x = -20.578}}}or {{{x = 14.578}}} Discard the negative solution as the width (x) must be a positive value.
{{{x = 14.6}}}
The width is 14.6 feet (to the nearest tenth of a foot).