The two masters and apprentices jointly produce a kind of parts. The master produces 10 more per hour than the apprentice. The master produces 7 hours, and the apprentice produces 4 hours, which just completes the production task of this part. When the task is completed, the number of parts produced by the apprentice is the master's (10/21), how many such parts are produced by the master and apprentice?
师徒二人共同生产一种零件，师父比徒弟每小时多生产10个，师傅生产了7小时，徒弟生产了4小时，正好完成这种零件的生产任务．完成任务时，徒弟生产零件的个数是师傅的(10/21)，师徒共生产这种零件多少个？
<gadget id="calculator">10 / 21</gadget>
<output>10/21 = around 0.47619</output>

<gadget id="calculator">10 * 7 * (10/21)</gadget>
<output>100/3 = around 33.333333</output>

<gadget id="calculator">7 * (10/21)</gadget>
<output>10/3 = around 3.333333</output>

<gadget id="calculator">4 - (10/3)</gadget>
<output>2/3 = around 0.666667</output>

<gadget id="calculator">(100/3) / (2/3)</gadget>
<output>50</output>

<gadget id="calculator">50 * 4</gadget>
<output>200</output>

<gadget id="calculator">50 + 10</gadget>
<output>60</output>

<gadget id="calculator">60 * 7</gadget>
<output>420</output>

<gadget id="calculator">200 + 420</gadget>
<output>620</output>

<result>620</result>