The length of the rectangle was reduced by 3 cm, and the width was increased by 4 cm

The length of the rectangle was reduced by 3 cm, and the width was increased by 4 cm to give a square. Find the side of the square if the area of the rectangle is 30 cm2.

For the solution, we introduce the variable x and y.
Let’s assume that the length of the rectangle is x and the width is y.
Whereas by condition the area of the rectangle is 30 cm2, then x * y = 30.
We also know that when the length of the rectangle was reduced by 3 cm, and the width was increased by 4 cm, we got a square, that is, x – 3 = y + 4.
Having solved the system, we get that y = 3, and x = 10, then the side of the square is 3 + 4 = 10 – 3 = 7 cm.