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Roberto and Granma!
After using the sieve of Eratosthenes, we found all of the prime numbers. After finding the prime numbers, we eliminated the ones that could not be the ages due to impossibility.
Plans to Solve/Investigate the Problem
We narrowed the choices down to 61, 71, 73 and 83 for the grandmother's age. The reversal of these numbers is Roberto's age. Then, we had to add ten years to the ages and triple Roberto's age and this must equal Granma's age.
Investigation/Exploration of the Problem
The only solution that will work is if Granma is 71 and Roberto is 17 now. This way, when you add 10 years to 17 and 71, you get 27 and 81. Then, when you triple 27, you get 81 which will be Granma's age ten years from now.