part is made of zinc-copper alloy. The ratio of the copper content of the part to the weight of the alloy is 9:25. The total weight of a part is 2.5 kg. How many kg of copper is needed to make such a part?
一种零件是有锌铜合金做成，零件的铜含量与合金重量的比是9：25，一个零件总重2.5千克，做一个这样的零件需要铜多少千克？
<gadget id="calculator">9 / 25</gadget>
<output>9/25 = around 0.36</output>

<gadget id="calculator">2.5 * (9/25)</gadget>
<output>0.9</output>

<result>0.9</result>