Master Wang processes 810 parts in 3 hours, and Master Li processes 580 parts in 2 hours. How many more parts does Master Li process per hour than Master Wang?
王师傅3小时加工810个零件，李师傅2小时加工580个零件，李师傅比王师傅每小时多加工多少个零件？
<gadget id="calculator">580 / 2</gadget>
<output>290</output>

<gadget id="calculator">810 / 3</gadget>
<output>270</output>

<gadget id="calculator">290 - 270</gadget>
<output>20</output>

<result>20</result>