If a tape recorder is sold at 10% off the original price, it can make a profit of 70 yuan, and if it is sold at 50% off the original price, it can make a profit of 100 yuan. What is the purchase price of this tape recorder?
一台收录机如果按原价的九折出售可获利70元，如果按原价的九五折出售可获利100元，那么这台收录机的进货价格是多少？
<gadget id="calculator">100 - 70</gadget>
<output>30</output>

<gadget id="calculator">95 / 100</gadget>
<output>19/20 = around 0.95</output>

<gadget id="calculator">90 / 100</gadget>
<output>9/10 = around 0.9</output>

<gadget id="calculator">(19/20) - (9/10)</gadget>
<output>1/20 = around 0.05</output>

<gadget id="calculator">30 / (1/20)</gadget>
<output>600</output>

<gadget id="calculator">600 * (9/10)</gadget>
<output>540</output>

<gadget id="calculator">540 - 70</gadget>
<output>470</output>

<result>470</result>