A cylindrical cistern is 4 meters deep and uses an average of 8 tons of water per day. After 7 days, the water in the pool decreases by 20% (1 ton per cubic meter of water). What is the area occupied by this pool?
一个圆柱形蓄水池深4米，平均每天用水8吨，7天后水池的水减少了20%(每立方米的水重1吨)，这个水池的占地面积是多少？
<gadget id="calculator">20 / 100</gadget>
<output>1/5 = around 0.2</output>

<gadget id="calculator">4 * (1/5)</gadget>
<output>4/5 = around 0.8</output>

<gadget id="calculator">7 / 1 / (4/5)</gadget>
<output>35/4 = around 8.75</output>

<gadget id="calculator">8 * (35/4)</gadget>
<output>70</output>

<result>70</result>