Answer:
Explanation:
So, we’re probably looking at a n9-m0 cusp, since adding 0 to a number gives a sum lower than adding 9 to a slightly smaller number, something that isn’t true elsewhere in the cycle.
We need a n9 where the sum n+9 is divisible by 3. 9 is divisible by 3 already, so n must be divisible by 3 as well. So, it’s 0, 3, 6, or 9.
Taking as the most likely 3 (because a 39 year old is more likely than a 9 year old, 69 year old, or 99 year old to have a child who doesn’t already know their father’s age) we’ll try 39, 40. 3+9=12, 4+0=4, 12/3=4, this is a possible solution.
Do the others work?
0+9=9, 1+0=1, 9/4=/=1
6+9=15, 7+0=7, 15/4=/=7
9+9=18, 1+0+0=1, 18/4=/=1
1+2+9=12, 1+3+0=4, 12/3=4
there are at least two possibles. the father was correct, the father cannot determine his age from what she has been told, she must guess. From what she knows of him, is it more likely that he’s 39, or 129, or even older?