Aunt Zhang took some RMB to the grain store to buy grain. If you buy rice with these RMB, you can buy 20 kilograms; if you buy flour, you can buy 15 kilograms. Later, Aunt Zhang bought 12 kilograms of rice, and the remaining RMB was used to buy flour. How much flour did Aunt Zhang buy?
张大妈带一些人民币到粮食店买粮食．这些人民币如果都买大米可以买20千克；如果都买面粉可以买15千克．后来，张大妈买了12千克大米，剩下的人民币去买了面粉．张大妈买了多少面粉？
<gadget id="calculator">1 / 20</gadget>
<output>1/20 = around 0.05</output>

<gadget id="calculator">(1/20) * 12</gadget>
<output>3/5 = around 0.6</output>

<gadget id="calculator">1 - (3/5)</gadget>
<output>2/5 = around 0.4</output>

<gadget id="calculator">1 / 15</gadget>
<output>1/15 = around 0.066667</output>

<gadget id="calculator">(2/5) / (1/15)</gadget>
<output>6</output>

<result>6</result>