Three years ago, Bethany was twice the age of her younger sister. In 5 years, her younger sister will be 16. How old is Bethany now?
First find how old Bethany's sister currently is: 16 years - 5 years = <T>subtract(16, 5)=11 years
Then find how old her sister was 3 years ago: 11 years - 3 years = <T>subtract(11, 3)=8 years
Then double that age to find how old Bethany was three years ago: 8 years * 2 = <T>multiply(8, 2)=16 years
Then add 3 years to that number to find how old Bethany is now: 16 years + 3 years = <T>add(16, 3)=19 years
