I am a fraction. My numerator is four less than my denominator. If you add two to both my numerator and denominator, my new value simplifies to two-thirds. What fraction am I?
6/10
Let denominator be d, numerator is d - 4. New fraction is (d - 4 + 2) / (d + 2) = (d - 2) / (d + 2) = 2/3. Cross multiplying gives 3(d - 2) = 2(d + 2) -> 3d - 6 = 2d + 4 -> d = 10. Numerator is 6. Fraction is 6/10 (or 3/5).
About this riddle
Math riddles hide a calculation inside a short story. Pull out the numbers, work out what is being asked, and watch for a trick such as a unit change.
Difficulty: Hard. More like this: Math riddles with answers or try Target 24 for a different kind of puzzle.
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