small river flows through towns A, B, and C. A steamboat travels between towns A and B, and the speed of the steamboat in still water is 11 km/h. There is a wooden boat ferry between towns B and C, and the speed of the wooden boat in still water is 3.5 km/h. It is known that the waterway between towns A and C is 50 kilometers apart, and the water velocity is 1.5 kilometers per hour. A person goes down the river from town A to town B, takes 1 hour to have lunch, and then goes down the river to town C in a wooden boat for 8 hours, then how many kilometers is the distance between towns A and B?
一条小河流过A，B，C三镇．A，B两镇之间有汽船来往，汽船在静水中的速度为11千米/时．B，C两镇之间有木船摆渡，木船在静水中的速度为3.5千米/时．已知A，C两镇水路相距50千米，水流速度为1.5千米/时．某人从A镇上船顺流而下到B镇，吃午饭用去1小时，接着乘木船又顺流而下到C镇，共用8小时，那么A，B两镇的距离是多少千米
<gadget id="calculator">3.5 + 1.5</gadget>
<output>5</output>

<gadget id="calculator">50 / 5</gadget>
<output>10</output>

<gadget id="calculator">10 - 7</gadget>
<output>3</output>

<gadget id="calculator">1 / 5</gadget>
<output>1/5 = around 0.2</output>

<gadget id="calculator">11 + 1.5</gadget>
<output>12.5</output>

<gadget id="calculator">1 / 12.5</gadget>
<output>0.08</output>

<gadget id="calculator">(1/5) - 0.08</gadget>
<output>0.12</output>

<gadget id="calculator">3 / 0.12</gadget>
<output>25</output>

<result>25</result>