For a minute, take off 2 years from the John's age. Then you have two quantities: the "corrected" John's age and the Mia's age. The first quantity is 2 times the second and they sum up to 32-2 = 30. x + 2x = 30 ====> 3x = 30 ====> x = 30/3 = 10. Thus Mia is 10 years old and John is 2x + 2 = 2*10 + 2 = 22 years old.