After the price reduction (3/10) of a computer, it is 2800 yuan. What is the original price?
一台电脑降价(3/10)后，是2800元，原价是多少元．
<gadget id="calculator">3 / 10</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_800 / (7/10)</gadget>
<output>4_000</output>

<result>4_000</result>