cuboid pool, the bottom is 2.5 meters long and 2 meters wide. The pool was originally full of water, and after (4/5) of the pool water was used up, another 1.8 cubic meters of water was injected. At this time, there is just half of the pool of water. How many meters deep is the pool?
一长方体水池，底面长2.5米，宽2米．水池原来存满水，用去(4/5)池水后，又注入1.8立方米的水．这时刚好有半池水，池深多少米？
<gadget id="calculator">1 / 2</gadget>
<output>1/2 = around 0.5</output>

<gadget id="calculator">4 / 5</gadget>
<output>4/5 = around 0.8</output>

<gadget id="calculator">1 - (4/5)</gadget>
<output>1/5 = around 0.2</output>

<gadget id="calculator">(1/2) - (1/5)</gadget>
<output>3/10 = around 0.3</output>

<gadget id="calculator">2.5 * 2</gadget>
<output>5</output>

<gadget id="calculator">1.8 / (3/10) / 5</gadget>
<output>1.2</output>

<result>1.2</result>