The chemical plant used 450 tons of coal in July, and the amount of coal used in August was 30% lower than that in July. How many tons of coal was used in August?
化工厂七月份用煤450吨，八月份用煤量比七月份减少三成，八月份用煤多少吨．
<gadget id="calculator">30 / 100</gadget>
<output>3/10 = around 0.3</output>

<gadget id="calculator">1 - (3/10)</gadget>
<output>7/10 = around 0.7</output>

<gadget id="calculator">450 * (7/10)</gadget>
<output>315</output>

<result>315</result>