The length of a side of a square is 5 cm. If a set of opposite sides is extended by 3 cm to obtain a rectangle, what is the area in square centimeters larger than the original square?
一个正方形的边长是5厘米，把它的一组对边延长3厘米得到一个长方形，它比原来正方形面积多多少平方厘米．
<gadget id="calculator">5 * 3</gadget>
<output>15</output>

<result>15</result>