The art group has 24 pieces of red chalk, the number of white chalk is 3/4 of red chalk, and 6/7 of blue chalk, how many pieces of blue chalk are there?
美术小组有红粉笔24支，白粉笔的支数是红粉笔的(3/4)，又是蓝粉笔的(6/7)，蓝粉笔有多少支？
<gadget id="calculator">3 / 4</gadget>
<output>3/4 = around 0.75</output>

<gadget id="calculator">6 / 7</gadget>
<output>6/7 = around 0.857143</output>

<gadget id="calculator">(3/4) / (6/7)</gadget>
<output>7/8 = around 0.875</output>

<gadget id="calculator">24 * (7/8)</gadget>
<output>21</output>

<result>21</result>