Master Zhang originally planned to process 630 parts in 6 hours, but actually processed 21 more parts per hour than the original plan. How many hours did it take to process these parts?
张师傅原计划用6小时加工零件630个，实际每小时比原计划多加工零件21个，实际加工完成这批零件共用多少小时？
<gadget id="calculator">630 / 6</gadget>
<output>105</output>

<gadget id="calculator">105 + 21</gadget>
<output>126</output>

<gadget id="calculator">630 / 126</gadget>
<output>5</output>

<result>5</result>