The ratio of length to width of a rectangle is 7:3. If the length is reduced by 12cm and the width is increased by 16cm, it becomes a square. What is the original square area Please use formula, not equation!

The ratio of length to width of a rectangle is 7:3. If the length is reduced by 12cm and the width is increased by 16cm, it becomes a square. What is the original square area Please use formula, not equation!

(12+16)÷(7-3)=7
Length: 7 × 7 = 49 (CM) width: 7 × 3 = 21 (CM)
Area: 49 × 21 = 1029 (square centimeter)