There are three piles of coal, A, B, and C, and the sum of the masses of coal in A and B is exactly equal to the mass of coal in pile C. Pile A has 15 tons more coal than Pile B, and Pile B has 60% less coal than Pile C. How many tons do these three piles of coal weigh?
有甲、乙、丙三堆煤，甲、乙两堆媒的质量之和正好与丙堆煤的质量相等．甲堆煤比乙堆煤多15吨，乙堆煤比丙堆煤少60%．这三堆煤共重多少吨？
<gadget id="calculator">60 / 100</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 - (2/5) - (2/5)</gadget>
<output>1/5 = around 0.2</output>

<gadget id="calculator">15 / (1/5)</gadget>
<output>75</output>

<gadget id="calculator">75 + 75</gadget>
<output>150</output>

<result>150</result>