Master Wang needs to process 48 parts, and has already processed 12 parts. The rest is calculated by processing 9 per hour, how many hours will it take to complete.
王师傅要加工48个零件，已经加工了12个．剩下的按每小时加工9个计算，还要多少小时才能完工．
<gadget id="calculator">48 - 12</gadget>
<output>36</output>

<gadget id="calculator">36 / 9</gadget>
<output>4</output>

<result>4</result>