If the purchase price is reduced by 8%, but the selling price remains unchanged, the profit (according to the purchase price) can be increased from the current P% to (P+10%), find P.
若进货价降低8%，而售出价不变，则利润(按照进货价而定)可由目前的P%增加到(P+10%)，求P．
<gadget id="calculator">15 / 100</gadget>
<output>3/20 = around 0.15</output>

<result>3/20 = around 0.15</result>