Question 304366
let the length of the sign be x feet

the poster length will be x-2 feet

since they are squares both sides are equal

x^2-(x-2)^2= 48 square feet

x^2-(x^2-4x+4) =48

x^2-x^2+4x-4=48

4x= 48+4
4x=52
x= 13 feet

poster will be  11 feet