If the length of a rectangle increases by 2/5 and the width decreases by 1/3, how does its area change?
一个长方形的长增加原来的(2/5)，宽减少原来的(1/3)，它的面积怎样变化？
<gadget id="calculator">7 * 2</gadget>
<output>14</output>

<gadget id="calculator">5 * 3</gadget>
<output>15</output>

<gadget id="calculator">14 / 15</gadget>
<output>14/15 = around 0.933333</output>

<result>14/15 = around 0.933333</result>