The planned cost of repairing the runway at the school is 40,000 yuan, but the actual cost is 15% lower than the plan. How much is the actual cost?
学校维修跑道，计划费用4万元，实际比计划节约15%，实际费用多少万元？
<gadget id="calculator">15 / 100</gadget>
<output>3/20 = around 0.15</output>

<gadget id="calculator">1 - (3/20)</gadget>
<output>17/20 = around 0.85</output>

<gadget id="calculator">4 * (17/20)</gadget>
<output>17/5 = around 3.4</output>

<result>17/5 = around 3.4</result>