Cai Xu took 18 yuan to buy coal. Because the price of coal dropped (1/4), the money bought 100 kg more coal than before. How much is the price of coal per kilogram?
蔡旭带18元钱去买煤，由于煤价降低了(1/4)，结果这些钱比原来多买了100千克煤．原来每千克煤价是多少元？
<gadget id="calculator">1 / 4</gadget>
<output>1/4 = around 0.25</output>

<gadget id="calculator">1 - (1/4)</gadget>
<output>3/4 = around 0.75</output>

<gadget id="calculator">(1/4) / 100 / (3/4)</gadget>
<output>1/300 = around 0.003333</output>

<gadget id="calculator">18 * (1/300)</gadget>
<output>3/50 = around 0.06</output>

<result>3/50 = around 0.06</result>