12/17+15/17+20/17+21/17=how much.
12/17+15/17+20/17+21/17=多少．
<gadget id="calculator">12 / 17</gadget>
<output>12/17 = around 0.705882</output>

<gadget id="calculator">15 / 17</gadget>
<output>15/17 = around 0.882353</output>

<gadget id="calculator">20 / 17</gadget>
<output>20/17 = around 1.176471</output>

<gadget id="calculator">21 / 17</gadget>
<output>21/17 = around 1.235294</output>

<gadget id="calculator">(12/17) + (15/17) + (20/17) + (21/17)</gadget>
<output>4</output>

<result>4</result>