Logical Puzzles

3. Jacob is 12 years old. He is 3 times as old as his brother. How old will Jacob be when he is twice as old?
 
Answer
16 years old.
4. If it takes 2 garage mechanics 3 hours to repair 6 cars, how many mechanics would it take to repair 22 cars in 5 hours?
 
Answer
5 mechanics, with a little time left over.