Xiaoling's typing speed is 7 per minute, which is 2 more than Xiaoming's typing per minute. How much can Xiaoming type in 4 minutes.
小玲的打字速度是每分钟7个，比小明每分钟多打字2个，小明4分钟能打字多少个．
<gadget id="calculator">7 - 2</gadget>
<output>5</output>

<gadget id="calculator">5 * 4</gadget>
<output>20</output>

<result>20</result>