Answer:
[tex]ls=3l_{J}[/tex]
Step-by-step explanation:
Let Sally's polygon be for example a square (As) where the area is equal to the square side and Jack (Aj) has a proportional one but Sally's is nine times larger than the Jack, then:
[tex]As=9A_{J}\\A_{J}=l^{2}_{J}\\As=9A_{J}\\As=l^{2}s\\replacing\\l^{2}s=9A_{J}\\l^{2}s=9l^{2}_{J}\\\sqrt{l^{2}s}=\sqrt{9l^{2}_{J}}\\ls=3l_{J}[/tex]
