A bottle of beverage, drink it (1/7) more 20 milliliters every day, just finish drinking it in 5 days. How many milliliters is this bottle of drink originally?
一瓶饮料，每天喝它的(1/7)还多20毫升，5天正好喝完．这瓶饮料原有多少毫升？
<gadget id="calculator">1 / 5</gadget>
<output>1/5 = around 0.2</output>

<gadget id="calculator">1 / 7</gadget>
<output>1/7 = around 0.142857</output>

<gadget id="calculator">(1/5) - (1/7)</gadget>
<output>2/35 = around 0.057143</output>

<gadget id="calculator">20 / (2/35)</gadget>
<output>350</output>

<result>350</result>