From A to B, it takes 16 hours by horse-drawn carriage and 4 hours by car. Now it takes a total of 6 hours to travel by horse-drawn carriage and then by car. How long does it take to take a horse-drawn carriage?
由甲地赴乙地，乘马车要16小时，乘汽车要4小时，现在先乘马车后乘汽车共花6小时，问乘马车多少小时？
<gadget id="calculator">4 / 1</gadget>
<output>4</output>

<gadget id="calculator">1 / 4</gadget>
<output>1/4 = around 0.25</output>

<gadget id="calculator">(1/4) * 6</gadget>
<output>3/2 = around 1.5</output>

<gadget id="calculator">(3/2) - 1</gadget>
<output>1/2 = around 0.5</output>

<gadget id="calculator">16 / 1</gadget>
<output>16</output>

<gadget id="calculator">1 / 16</gadget>
<output>1/16 = around 0.0625</output>

<gadget id="calculator">(1/4) - (1/16)</gadget>
<output>3/16 = around 0.1875</output>

<gadget id="calculator">(1/2) / (3/16)</gadget>
<output>8/3 = around 2.666667</output>

<result>8/3 = around 2.666667</result>