Create a function that takes two arguments: a father's current age fAge and his son's current age sAge. Сalculate how many years ago the father was twice as old as his son, or in how many years he will be twice as old.
ageDifference(36, 7) ➞ 22
// 22 years from now, the father will be 58 years old and his son will be 29 years old.
ageDifference(55, 30) ➞ 5
// 5 years ago, the father was 50 years old and his son was 25 years old.
ageDifference(42, 21) ➞ 0
N/A