15 thumbtacks weigh about 10 grams, and how many thumbtacks weigh about 30 grams.
15枚图钉大约重10克，多少枚图钉大约重30克．
<gadget id="calculator">10 / 15</gadget>
<output>2/3 = around 0.666667</output>

<gadget id="calculator">30 / (2/3)</gadget>
<output>45</output>

<result>45</result>