If the length of a rectangle is reduced by 9cm and the width is increased by 6cm, it will become a square, and the areas of the two figures are equal . please!

If the length of a rectangle is reduced by 9cm and the width is increased by 6cm, it will become a square, and the areas of the two figures are equal . please!

The length is xcm and the width is YCM
x-9=y+6
xy=(x-9)(y+6)
The solution
x=27
y=12