1989 AHSME Problems/Problem 3

Let $x$ be the width of a rectangle so that the side of the square is $3x$. Since $2(3x)+2(x)=24$ we have $x=3$. Thus the area of the square is $(3\cdot3)^2=81$. The problems on this page are copyrighted by the Mathematical Association of America's American Mathematics Competitions. AMC logo.png