Two cars A and B are traveling towards each other from A and B respectively. They start at 7:30 am at the same time. The speed ratio of A and B is 3:4. They meet at a distance of 9 kilometers from the midpoint. A , How many kilometers are there between B and her?
甲、乙两辆汽车分别从A、B两地相向而行，它们上午7：30同时出发，甲、乙两车的速度比是3：4，它们在距离中点9千米处相遇，A、B两她相距多少千米？
<gadget id="calculator">1 / 2</gadget>
<output>1/2 = around 0.5</output>

<gadget id="calculator">3 + 4</gadget>
<output>7</output>

<gadget id="calculator">3 / 7</gadget>
<output>3/7 = around 0.428571</output>

<gadget id="calculator">(1/2) - (3/7)</gadget>
<output>1/14 = around 0.071429</output>

<gadget id="calculator">9 / (1/14)</gadget>
<output>126</output>

<result>126</result>