4. The perimeter of a rectangle is 126 cm, and the difference between its sides is $37 \mathrm{~cm}$. Find the area of the rectangle.
4. 5) $126: 2=63$ cm - the sum of the length and width of the rectangle;
2) $63+37=100$ cm - the doubled length of the rectangle;
3) $100: 2=50$ cm - the length of the rectangle;
4) $63-50=13$ cm - the width of the rectangle;
5) $50 \times 13=650 \mathrm{~cm}^{2}$ - the area of the rectangle.

Answer: the area of the rectangle is $650 \mathrm{~cm}^{2}$.