A coal mine produced 21 million tons of coal last year, 30% less than last year. How many tons of coal will it produce this year?
某煤矿去年产煤2100万吨，比去年少30%，今年产煤多少万吨？
<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">2_100 * (7/10)</gadget>
<output>1_470</output>

<result>1_470</result>