Answer:
25,31,37
Step-by-step explanation:
n should be positive integer number. The three numbers in both sequences have different term number n but same value. We can equalize each nth term in the question to "a" which represents one of the three numbers.
a=2n-1, then n=(a+1)/2
a=3n+1, then n=(a-1)/3
remember the two n above are different but both should be positive integer. That means, we have to find the "a" number that gives me an integer n for the first equation. The possible numbers between 20 to 40 are 22,25,28,31,34,37,40.
The possible numbers for the second equation are 21,23,25,27,29,31,33,35,37,39.
Now find the common numbers between the two sets above. They are 25,31,37
