worker plans to produce 80 parts in 4 hours. After the technology is improved, 180 parts are processed in 4.5 hours. How many more parts are produced per hour now than before?
一个工人计划4小时生产零件80个，技术改进后，4.5小时加工零件180个，现在每小时比原来每小时多做多少个零件？
<gadget id="calculator">180 / 4.5</gadget>
<output>40</output>

<gadget id="calculator">80 / 4</gadget>
<output>20</output>

<gadget id="calculator">40 - 20</gadget>
<output>20</output>

<result>20</result>