The price of a commodity has been reduced by 210 yuan after the 30% discount. What is the current price?
一种商品七折销售后价格降低了210元，现价多少元．
<gadget id="calculator">70 / 100</gadget>
<output>7/10 = around 0.7</output>

<gadget id="calculator">1 - (7/10)</gadget>
<output>3/10 = around 0.3</output>

<gadget id="calculator">210 / (3/10)</gadget>
<output>700</output>

<gadget id="calculator">700 - 210</gadget>
<output>490</output>

<result>490</result>