The Hongxing factory used 120 tons of coal in the first six months, and 102 tons of coal in the second half of the year. Calculated on the basis of 500 yuan per ton of coal, how much is the average monthly coal saving in the second half of the year compared to the first half of the year?
红星工厂前6个月用煤120吨，后半年用煤102吨．每吨煤按500元计算，后半年比前半年平均每月用煤节约多少元？
<gadget id="calculator">120 - 102</gadget>
<output>18</output>

<gadget id="calculator">500 / 6</gadget>
<output>250/3 = around 83.333333</output>

<gadget id="calculator">18 * (250/3)</gadget>
<output>1_500</output>

<result>1_500</result>