Question 999866
w and L, width and length;
{{{system(L=4+2w,wL=30)}}}


This will give a quadratic equation allowing to solve first for w.


{{{w(2w+4)=30}}}

{{{2w^2+4w-30=0}}}

{{{w^2+2w-15=0}}}
Formula for general solution of a quadratic equation is what could use, but try factoring first.