Configure a kind of gunpowder, the ratio of fire nitrate, sulfur, and charcoal is 15:2:3, and each of the three materials has 90 kilograms. If the sulfur is just used up, how many kilograms of fire nitrate will be needed.
配置一种火药，火硝、硫磺、木炭的比是15：2：3，三种材料各有90千克，如果硫磺正好用完，那么火硝还需要多少千克．
<gadget id="calculator">90 / 2</gadget>
<output>45</output>

<gadget id="calculator">45 * 15</gadget>
<output>675</output>

<gadget id="calculator">675 - 90</gadget>
<output>585</output>

<result>585</result>