A small bag of "Xizhilang" jelly is 3.6 yuan. "RT-Mart" launched a special promotion of "buy 3, get 1 free" for the anniversary celebration. Xiaoying bought 3 small bags at one time. How much is each small bag cheaper on average?
一小袋"喜之郎"果冻3.6元，"大润发"商场周年庆典，特推出"买3送1"的优惠活动，小英就一次性购买了3小袋，平均每小袋便宜多少元？
<gadget id="calculator">3 / 4</gadget>
<output>3/4 = around 0.75</output>

<gadget id="calculator">3.6 * (3/4)</gadget>
<output>2.7</output>

<gadget id="calculator">3.6 - 2.7</gadget>
<output>0.9</output>

<result>0.9</result>