cistern is (5/4) m deep and the water surface is (1/5) m away from the mouth of the cistern. What is the depth of the cistern in m?
一个蓄水池，水深(5/4)m，水面距池口(1/5)m，这个蓄水池的深度是多少m．
<gadget id="calculator">5 / 4</gadget>
<output>5/4 = around 1.25</output>

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

<gadget id="calculator">(5/4) + (1/5)</gadget>
<output>29/20 = around 1.45</output>

<result>29/20 = around 1.45</result>