If the purchase price of a certain commodity is reduced by 15%, and the selling price remains unchanged, the profit rate increases by 21%, what is the current profit rate?
某种商品由于进货的价格降低15%，售出价保持不变，使得利润率提高了21%，则现在的利润率是多少．
<gadget id="calculator">19 / 100</gadget>
<output>19/100 = around 0.19</output>

<gadget id="calculator">21 / 100</gadget>
<output>21/100 = around 0.21</output>

<gadget id="calculator">(19/100) + (21/100)</gadget>
<output>2/5 = around 0.4</output>

<result>2/5 = around 0.4</result>