The two piles of coal, A and B, weigh 18 tons in total. (1/4) of the coal in pile A is equal to (1/5) of the coal in pile B. How many tons of coal is in pile A?
甲乙两堆煤共重18吨，甲堆煤的(1/4)等于乙堆煤的(1/5)，甲堆煤多少吨？
<gadget id="calculator">1 / 4</gadget>
<output>1/4 = around 0.25</output>

<gadget id="calculator">1 / 5</gadget>
<output>1/5 = around 0.2</output>

<gadget id="calculator">(1/4) / (1/5)</gadget>
<output>5/4 = around 1.25</output>

<gadget id="calculator">1 + (5/4)</gadget>
<output>9/4 = around 2.25</output>

<gadget id="calculator">18 / (9/4)</gadget>
<output>8</output>

<result>8</result>