There is some rice in the grain station, 20% of the total is sold on the first day, and 70 tons are sold on the second day. At this time, the ratio of the remaining rice to the sold rice is 5:3. How many tons of these rice are there?
粮站有一些大米，第一天卖出总量的20%，第二天卖出70吨，这时剩下的大米和已经卖出大米的比是5：3，这些大米原有多少吨？
<gadget id="calculator">20 / 100</gadget>
<output>1/5 = around 0.2</output>

<gadget id="calculator">5 / 8</gadget>
<output>5/8 = around 0.625</output>

<gadget id="calculator">1 - (1/5) - (5/8)</gadget>
<output>7/40 = around 0.175</output>

<gadget id="calculator">70 / (7/40)</gadget>
<output>400</output>

<result>400</result>