pair of sports shoes originally sold for 250 yuan. "May 1st" sale is 30% off, and each pair only sells for how much yuan.
一双运动鞋原来卖250元．"五一"促销时打七折出售，每双只卖多少元．
<gadget id="calculator">70 / 100</gadget>
<output>7/10 = around 0.7</output>

<gadget id="calculator">250 * (7/10)</gadget>
<output>175</output>

<result>175</result>