The selling price of a mobile phone is 1800 yuan, and the profit of 20% can be obtained after the sale of this mobile phone. What is the purchase price of this mobile phone?
一部手机的售价是1800元，这部手机售出后可获20%的利润，这部手机的进货价为多少．
<gadget id="calculator">20 / 100</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_800 / (6/5)</gadget>
<output>1_500</output>

<result>1_500</result>