The experimental primary school saved 40 tons of water in April compared to March, and it is known that the water consumption in April is 80% of that in March. How many tons of water is used in April?
实验小学四月份比三月份节约用水40吨，已知四月份用水量是三月份的80%．四月份用水多少吨？
<gadget id="calculator">80 / 100</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">40 / (1/5)</gadget>
<output>200</output>

<gadget id="calculator">200 - 40</gadget>
<output>160</output>

<result>160</result>