If you sell a pen for 12 yuan, you can earn 60%; if you sell it for 10 yuan, how much can you earn?
1支钢笔，若卖12元，则可赚60%；若卖10元，则可赚多少元．
<gadget id="calculator">60 / 100</gadget>
<output>3/5 = around 0.6</output>

<gadget id="calculator">1 + (3/5)</gadget>
<output>8/5 = around 1.6</output>

<gadget id="calculator">12 / (8/5)</gadget>
<output>15/2 = around 7.5</output>

<gadget id="calculator">10 - (15/2)</gadget>
<output>5/2 = around 2.5</output>

<result>5/2 = around 2.5</result>