The total number of boys and girls in a class is 50. The average age of all the boys is 20 years, and the average age of all the girls is 15 years. If the total number of boys is 6 more than the total number of girls, find the average age (in years) of the whole class.
1
16.5
2
18.2
3
17.4
4
18.5
5
17.8