15 thumbtacks weigh about 10g, and how many thumbtacks weigh about 20g.
15枚图钉大约重10g，多少枚图钉大约重20g．
<gadget id="calculator">10 / 15</gadget>
<output>2/3 = around 0.666667</output>

<gadget id="calculator">20 / (2/3)</gadget>
<output>30</output>

<result>30</result>