A store sells a kind of leather boots, the original price is 120 yuan per pair, and an average of 5 pairs are sold every day. During the Spring Festival, a 20% discount will increase the daily sales volume by 200%. By what percentage did sales increase?
某商店销售一种皮靴，原价每双120元，每天平均售出5双．春节期间，八折优惠，每天的销售量增加200%．销售额增加了百分之几？
<gadget id="calculator">80 / 100</gadget>
<output>4/5 = around 0.8</output>

<gadget id="calculator">200 / 100</gadget>
<output>2</output>

<gadget id="calculator">1 + 2</gadget>
<output>3</output>

<gadget id="calculator">120 * (4/5) * 5 * 3</gadget>
<output>1_440</output>

<gadget id="calculator">120 * 5</gadget>
<output>600</output>

<gadget id="calculator">1_440 - 600</gadget>
<output>840</output>

<gadget id="calculator">840 / 600</gadget>
<output>7/5 = around 1.4</output>

<result>7/5 = around 1.4</result>