Lenovo Computer Store has a batch of computers, part of which has been sold, and the remaining 2/3. When 80 more computers are sold, the ratio of the sold to the remaining is 4:1. How many computers are left? Sell?
联想电脑专卖店有一批电脑，已经卖了一部分，已卖的是剩下的2/3，当再卖80台时，已卖的和剩下的比是4：1，还剩多少台电脑没卖？
<gadget id="calculator">4 + 1</gadget>
<output>5</output>

<gadget id="calculator">4 / 5</gadget>
<output>4/5 = around 0.8</output>

<gadget id="calculator">2 + 3</gadget>
<output>5</output>

<gadget id="calculator">2 / 5</gadget>
<output>2/5 = around 0.4</output>

<gadget id="calculator">(4/5) - (2/5)</gadget>
<output>2/5 = around 0.4</output>

<gadget id="calculator">80 / (2/5)</gadget>
<output>200</output>

<gadget id="calculator">1 / 5</gadget>
<output>1/5 = around 0.2</output>

<gadget id="calculator">200 * (1/5)</gadget>
<output>40</output>

<result>40</result>