The fare of an air-conditioned bus on a certain road is 1.8 yuan after a discount, which is 80% more expensive than the fare of an ordinary bus. How much is the fare of an ordinary bus?
某路空调公交车的票价优惠后是1.8元，比普通公交车的票价贵80%，普通公交的票价是多少元？
<gadget id="calculator">80 / 100</gadget>
<output>4/5 = around 0.8</output>

<gadget id="calculator">1 + (4/5)</gadget>
<output>9/5 = around 1.8</output>

<gadget id="calculator">1.8 / (9/5)</gadget>
<output>1</output>

<result>1</result>