Today is Jack’s birthday and Jill’s birthday. Jack is five and Jill is nine.

1. How many years ago was Jill twice as old as Jack?

2. When Jack is three quarters as old as Jill, how old will Jill be?

3. When Jill was three times as old as Jack, how old was Jack?

4. When Jill is four times as old as Jack is today, how old will Jack be?