There is a TV set in a shopping mall. If the price of each set is reduced by 20% from the original price, there will still be a profit of 50 yuan. If the price is reduced by 25%, the loss will still be 30 yuan. What is the purchase price of each TV set?
商场有一种电视机，如果每台按原价降价20%，还盈利50元，如果降价25%，还亏本30元，求电视机进价是每台多少元？
<gadget id="calculator">20 / 100</gadget>
<output>1/5 = around 0.2</output>

<gadget id="calculator">1 - (1/5)</gadget>
<output>4/5 = around 0.8</output>

<gadget id="calculator">50 + 30</gadget>
<output>80</output>

<gadget id="calculator">25 / 100</gadget>
<output>1/4 = around 0.25</output>

<gadget id="calculator">(1/4) - (1/5) - 1</gadget>
<output>-19/20 = around -0.95</output>

<gadget id="calculator">1 + (-19/20)</gadget>
<output>1/20 = around 0.05</output>

<gadget id="calculator">80 / (1/20)</gadget>
<output>1_600</output>

<gadget id="calculator">(4/5) * 1_600</gadget>
<output>1_280</output>

<gadget id="calculator">1_280 - 50</gadget>
<output>1_230</output>

<result>1_230</result>