If the length of a rectangle is increased by 3 cm and the width by 5 cm, the area of the resulting square will be 89 cm2 larger than the area of the original rectangle. Find the area of the original rectangle.
把一个长方形的长增加3厘米，宽增加5厘米，所得正方形的面积比原来长方形的面积增加89平方厘米，求原长方形的面积．
<gadget id="calculator">13 - 3</gadget>
<output>10</output>

<gadget id="calculator">13 - 5</gadget>
<output>8</output>

<gadget id="calculator">10 * 8</gadget>
<output>80</output>

<result>80</result>