A construction site shipped 78 tons of cement, but the steel products shipped were 12 tons less than cement. The tonnage of stones shipped is twice the total tonnage of cement and steel. How many tons of stones are shipped?
一个建筑工地运来水泥78吨，运来的钢材比水泥少12吨．运来石子的吨数是水泥和钢材的总吨数的2倍．运来石子多少吨？
<gadget id="calculator">78 - 12</gadget>
<output>66</output>

<gadget id="calculator">66 + 78</gadget>
<output>144</output>

<gadget id="calculator">144 * 2</gadget>
<output>288</output>

<result>288</result>