Xiao Ming wants to go from point A to point B within the planned time. If he travels 4 kilometers more per hour, the ratio of the time required to complete the journey to the time originally planned is 7:9. If you travel 2 kilometers, you will arrive 40 minutes later than the original plan. How many kilometers are there between A and B?
小明在计划的时间内要从A地到B地，如果他每小时多行4千米，那么走完全程所需的时间和原来计划用的时间的比是7：9，如果他每小时少行2千米，那么就要比原计划晚40分钟到达，A、B两地相距多少千米？
<gadget id="calculator">7 / 9</gadget>
<output>7/9 = around 0.777778</output>

<gadget id="calculator">(7/9) * 4</gadget>
<output>28/9 = around 3.111111</output>

<gadget id="calculator">1 - (7/9)</gadget>
<output>2/9 = around 0.222222</output>

<gadget id="calculator">(28/9) / (2/9)</gadget>
<output>14</output>

<gadget id="calculator">14 - 2</gadget>
<output>12</output>

<gadget id="calculator">2 / 3</gadget>
<output>2/3 = around 0.666667</output>

<gadget id="calculator">(2/3) / 2</gadget>
<output>1/3 = around 0.333333</output>

<gadget id="calculator">12 * (1/3) * 14</gadget>
<output>56</output>

<result>56</result>