A commodity sold at 85% last year can earn 25% profit. Due to the cost reduction this year, if you sell at 75% of the same price, you can still get a 30% profit. So this year's purchase price is what fraction of last year?
一种商品，去年按85%出售，能获25%的利润．由于今年成本降低，按同样的定价的75%出售，仍能获30%的利润．那么今年的买入价是去年的几分之几？
<gadget id="calculator">75 / 100</gadget>
<output>3/4 = around 0.75</output>

<gadget id="calculator">30 / 100</gadget>
<output>3/10 = around 0.3</output>

<gadget id="calculator">1 + (3/10)</gadget>
<output>13/10 = around 1.3</output>

<gadget id="calculator">(3/4) / (13/10)</gadget>
<output>15/26 = around 0.576923</output>

<gadget id="calculator">1 * (15/26)</gadget>
<output>15/26 = around 0.576923</output>

<gadget id="calculator">85 / 100</gadget>
<output>17/20 = around 0.85</output>

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

<gadget id="calculator">1 + (1/4)</gadget>
<output>5/4 = around 1.25</output>

<gadget id="calculator">(17/20) / (5/4)</gadget>
<output>17/25 = around 0.68</output>

<gadget id="calculator">1 * (17/25)</gadget>
<output>17/25 = around 0.68</output>

<gadget id="calculator">(15/26) / (17/25)</gadget>
<output>375/442 = around 0.848416</output>

<result>375/442 = around 0.848416</result>