To celebrate the New Year, I bought 12 red balloons. The yellow balloons I bought were red balloons (3/4), and the yellow balloons were blue balloons (1/2). How many blue balloons did you buy?
为庆祝新年买了12个红气球，买的黄气球是红气球的(3/4)，黄气球又是蓝气球的(1/2)．蓝气球买了多少个？
<gadget id="calculator">3 / 4</gadget>
<output>3/4 = around 0.75</output>

<gadget id="calculator">1 / 2</gadget>
<output>1/2 = around 0.5</output>

<gadget id="calculator">(3/4) / (1/2)</gadget>
<output>3/2 = around 1.5</output>

<gadget id="calculator">12 * (3/2)</gadget>
<output>18</output>

<result>18</result>