During the "May 1st" Golden Week, a product is sold with a 30% discount. The original price is 100 yuan, how much is it cheaper?
"五一"黄金周，一种商品打七折销售，原价100元，便宜了多少元．
<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">100 * (3/10)</gadget>
<output>30</output>

<result>30</result>