After 30 kg of salt water with 15% salt content is diluted to 5% salt water, how many kilograms of salt water is there at this time?
含盐15%的盐水30千克，稀释成含盐5%的盐水后，这时盐水有多少千克．
<gadget id="calculator">15 / 100</gadget>
<output>3/20 = around 0.15</output>

<gadget id="calculator">5 / 100</gadget>
<output>1/20 = around 0.05</output>

<gadget id="calculator">(3/20) / (1/20)</gadget>
<output>3</output>

<gadget id="calculator">30 * 3</gadget>
<output>90</output>

<result>90</result>