pair of sports shoes is currently sold at a 20% discount for 100 yuan. What is the original price of this pair of sports shoes?
一双运动鞋现在以八折售出是100元，这双运动鞋的原价是多少元．
<gadget id="calculator">80 / 100</gadget>
<output>4/5 = around 0.8</output>

<gadget id="calculator">100 / (4/5)</gadget>
<output>125</output>

<result>125</result>