During the summer vacation, Xiaoqiang insisted on running every day, and made a record of the distance he ran. If he runs 650 meters on the last day of summer vacation, he will run 595 meters per day on average; if he runs 770 meters on the last day, he will run 598 meters per day;
暑假期间，小强每天都坚持跑步，并对所跑的路程作了记录．如果他在暑假的最后一天跑650米，则平均每天跑595米；如果他最后一天跑770米，则每天跑598米；如果他想平均每天跑600米，那么最后一天应跑多少米．
<gadget id="calculator">770 - 650</gadget>
<output>120</output>

<gadget id="calculator">598 - 595</gadget>
<output>3</output>

<gadget id="calculator">120 / 3</gadget>
<output>40</output>

<gadget id="calculator">600 * 40</gadget>
<output>24_000</output>

<gadget id="calculator">595 * 40</gadget>
<output>23_800</output>

<gadget id="calculator">23_800 - 650</gadget>
<output>23_150</output>

<gadget id="calculator">24_000 - 23_150</gadget>
<output>850</output>

<result>850</result>