The old lathe produces 90 parts in 18 hours, and the new lathe produces 315 parts in 3 hours. How many times more parts can the new lathe produce per unit time than the old lathe?
旧车床18小时生产90个零件，新车床3小时生产315个零件．新车床单位时间内生产的零件是旧车床的几倍？
<gadget id="calculator">315 / 3</gadget>
<output>105</output>

<gadget id="calculator">90 / 18</gadget>
<output>5</output>

<gadget id="calculator">105 / 5</gadget>
<output>21</output>

<result>21</result>