Process a batch of parts, plan to process 350 per day, and complete in 12 days. Actually process 420 pieces per day, how many days can it be completed? (Solve with ratio)
加工一批零件，计划每天加工350个，12天完成．实际每天加工420个，多少天可以完成？(用比例解)
<gadget id="calculator">350 * 12</gadget>
<output>4_200</output>

<gadget id="calculator">4_200 / 420</gadget>
<output>10</output>

<result>10</result>