<PRE><B>Question 1171110</B>
u, the uniform width of the border around the pool


total area of pool AND border,  {{{(30+2u)(40+2u)}}}


Area of just the pool, {{{30*40=1200}}}


Area of just the border around pool, {{{(30+2u)(40+2u)-30*40=296}}};
Simplify and solve for u.


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{{{(30)(40)+2*40u+2*30u+4u^2-(30)(40)=296}}}
{{{2(30+40)u+4u^2=296}}}
{{{70u+2u^2=148}}}
{{{35u+u^2=74}}}
{{{u(35+u)=74}}}-------------looking for two factors of 74, which differ by 35, {{{highlight(u=2)}}}  will fit this.</PRE>