A bamboo pole is (9/5) meters long. Insert one end of the bamboo pole vertically into a cement pool 5/4 meters deep, and mark A at the junction of the water surface and the bamboo pole; Mark B at the junction of the bamboo poles, find the length of the distance between A and B.
一根竹竿长(9/5)米，把竹竿一端垂直插入5/4米深的水泥水池中，在水面与竹竿交界的地方做记号A；再把竹竿另一端垂直插入水池中，在水面与竹竿交界的地方做记号B，求A、B间有多长．
<gadget id="calculator">5 / 4</gadget>
<output>5/4 = around 1.25</output>

<gadget id="calculator">(5/4) * 2</gadget>
<output>5/2 = around 2.5</output>

<gadget id="calculator">9 / 5</gadget>
<output>9/5 = around 1.8</output>

<gadget id="calculator">(5/2) - (9/5)</gadget>
<output>7/10 = around 0.7</output>

<result>7/10 = around 0.7</result>