This seems to be a variation of the brain teaser about having 30 cents and one is not a nickel - but the other is. If the question is what two coins equal 25 cents, the answer could be
"two bits". In colonial times, each bit was worth an eight of a dollar, so two bits was 25 cents. You may recognize the reference to bits in the phrase "shave and a haircut, two bits".
20 cent piece, and a half dime (yes these are both american coinage)
