其它
The average of John and Leo's ages is Kelly's age. The average of Kelly and Mila's ages is Leo's age. Of the four children, John is the youngest and Mila the oldest. The average of John and Mila's ages is 11.  What is the total of the ages of Kelly and Leo? 
Overseas Competition->Knowledge Point->Word Problem Modules->Average Problems 
PMC 2019 21 