John has just turned 39.  3 years ago, he was twice as old as James will be in 6 years.  If James' older brother is 4 years older than James, how old is James' older brother?
John was 39-3=<T>subtract(39, 3)=36 years old 3 years ago
So that means in 6 years James will be 36/2=<T>divide(36, 2)=18.0 years old
So right now James is 18-6=<T>subtract(18, 6)=12 years old
So James's older brother is 12+4=<T>add(12, 4)=16 years old
