Mr. Li takes the bus to work, and it takes 50 minutes to walk to get off work; it takes 70 minutes to walk all the way. How many minutes will it take for all the rides.
李老师上班坐车，下班步行共用50分钟；如果全部步行要用70分钟．全部坐车要用多少分钟．
<gadget id="calculator">70 / 2</gadget>
<output>35</output>

<gadget id="calculator">50 - 35</gadget>
<output>15</output>

<gadget id="calculator">15 * 2</gadget>
<output>30</output>

<result>30</result>