Question 948985
Pool area,  {{{20*10}}}

Total area, {{{(x+20)(x+10)}}}.

JUST the path area, {{{(x+20)(x+10)-20*10}}}.



Function, {{{A(x)=(x+20)(x+10)-20*10}}}
{{{A(x)=x^2+20x+10x+20*10-20*10}}}
{{{highlight(A(x)=x^2+30x)}}}