Uncle Wang has to make 600 parts, 90 of which were made in the first 3 hours. How many hours will it take to make all the parts? (Solve with ratio)
王叔叔要做600个零件，前3个小时做了90个．要做完全部零件，还需要几个小时？(用比例解)
<gadget id="calculator">600 - 90</gadget>
<output>510</output>

<gadget id="calculator">90 / 3</gadget>
<output>30</output>

<gadget id="calculator">510 / 30</gadget>
<output>17</output>

<result>17</result>