Question 282287
l=3w-1
A=lw
A=310
310=lw
310=(3w-1)w
310=3w^2-w
{{{0=3w^2-w-310}}}
w=10.33333 or 31/3 ft so l=3(31/3)-1=30ft
*[invoke quadratic "w", 3, -1, -310]