A bottle of edible oil is 55 yuan, and during the Spring Festival, shopping malls hold a "buy 2 bottles, get 1 free" activity. Uncle Zhang brought back a total of 18 bottles of this kind of cooking oil. How much did he pay for these cooking oils?
一种食用油每瓶55元，春节期间商场举行"买2瓶送1瓶"的活动．张叔叔连买带送一共拿回来18瓶这样的食用油，他买这些食用油一共付了多少元？
<gadget id="calculator">12 * 15</gadget>
<output>180</output>

<result>180</result>