There are two piles of coal, A and B, pile A uses 18 tons, and pile B uses 7.5 tons. The remaining coal of the two piles is just equal. It is known that the coal in pile B originally belonged to pile A (5/8), and pile A originally How many tons of coal?
甲、乙两堆煤，甲堆用去18吨，乙堆用去7.5吨，两堆煤剩下的正好相等，已知原来乙堆煤是甲堆的(5/8)，甲堆原有煤多少吨？
<gadget id="calculator">18 - 7.5</gadget>
<output>10.5</output>

<gadget id="calculator">5 / 8</gadget>
<output>5/8 = around 0.625</output>

<gadget id="calculator">1 - (5/8)</gadget>
<output>3/8 = around 0.375</output>

<gadget id="calculator">10.5 / (3/8)</gadget>
<output>28</output>

<result>28</result>