The area of a rectangle is 15 square meters. If the length is multiplied by 4 and the width remains the same, what is the area of the rectangle now?
一个长方形的面积是15平方米，如果把长乘4，宽不变，那么现在长方形的面积应该是多少．
<gadget id="calculator">15 * 4</gadget>
<output>60</output>

<result>60</result>