I have two coins in my pocket that add up to the value of 30 cents. One of them is not a nickel. What two coins do I have in my pocket? (This riddle uses US currency, which means that the only coins available for the riddle are: penny (1c), nickel (5c), dime (10c) and quarter (25c))
The answer is a quarter and a nickel. Some might angrily retort that one of them should not be a nickel and that is correct. One of them is not a nickel, the other one is. We commonly place such simple yet seemingly unbreakable barriers in our minds. If you cannot solve a problem, take a step back and try to look past the barriers.