Question

A square and a rectangle have equal areas. The length of the rectangle is 9 cm longer than the side of the square and the width of the recangle is 6 cm shorter than the side of the square. How long is the side of the square?

Answer 1

side of square --- x
area of square = x^2

length of rectangle = +9
width of rectangle = x-6
area of rectangle = (x+9)(x-6)

It says the areas are equal

so solve
(x+9)(x-6) = x^2