5.2-meter bamboo pole is inserted vertically into the river. 2.15 meters out of the water, 0.45 meters into the mud, how deep is the river?
一根5.2米的竹竿垂直插入河中．露出水面有2.15米，插入泥中有0.45米，河水有多深？
<gadget id="calculator">5.2 - 0.45 - 2.15</gadget>
<output>2.6</output>

<result>2.6</result>