After the price of residential water is increased by (1/5), it is 1.8 yuan per cubic meter. What is the price per cubic meter before the price increase?
居民用水价格提高(1/5)后，每立方米是1.8元，求提价前每立方米的价格，列式是多少
<gadget id="calculator">1 / 5</gadget>
<output>1/5 = around 0.2</output>

<gadget id="calculator">1 + (1/5)</gadget>
<output>6/5 = around 1.2</output>

<gadget id="calculator">1.8 / (6/5)</gadget>
<output>1.5</output>

<result>1.5</result>