A father is currently 36 years old, while his young daughter is 6 years old. In how many years will the father's age be exactly three times his daughter's age?
9 years
Let y be the years. 36 + y = 3(6 + y). Expanding gives 36 + y = 18 + 3y, which simplifies to 2y = 18, so y = 9. In 9 years, they will be 45 and 15.
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: Easy. More like this: Math riddles with answers or try Target 24 for a different kind of puzzle.
More math riddles
I am thinking of a two-digit number. If you reverse my digits and add the new number to me, the sum is 88. The difference between my two digits is 2. What number am I?
There are 18 eggs in a box and 7 are taken out. How many eggs are left?
Leo gets 3 bees on Monday and 8 bees on Tuesday, then gives away 5. How many bees are left?
One pumpkin costs 3 dollars. How many dollars do 3 pumpkins cost?
I am an even number between 20 and 40. I am divisible by 3, 4, and 6, but I am not a perfect square. What number am I?
I start with a single bacterium. Every minute, every bacterium in the colony splits into two. It takes 60 minutes to completely fill a petri dish. How long did it take for the dish to be exactly half full?