The school planned to use (4/5) tons of coal in October, but actually saved (1/8) tons compared to the plan. How many tons of coal is actually used?
学校计划十月份用煤(4/5)吨，实际比计划节约了(1/8)吨．实际用煤多少吨？
<gadget id="calculator">4 / 5</gadget>
<output>4/5 = around 0.8</output>

<gadget id="calculator">1 / 8</gadget>
<output>1/8 = around 0.125</output>

<gadget id="calculator">(4/5) - (1/8)</gadget>
<output>27/40 = around 0.675</output>

<result>27/40 = around 0.675</result>