A father is 22 years older than his son. In 10 years he will be twice as old as the son. How old is the son now?

1. Let the son be x and the father x + 22. 2. In 10 years: x + 32 = 2(x + 10), so x + 32 = 2x + 20 and x = 12. 3. Check: father 34 now, 44 later; son 22 later; 44 = 2 × 22. 34 is the father's age. _Source: Wikipedia, Elementary algebra, Linear equations with two variables_