From the days I started to learn Maths, I've have been taught that
Adding Odd times Odd numbers the Answer always would be Odd; e.g., $$3 + 5 + 1 = 9$$
OK, but look at this question
This question was solved and the answer was 30, how it was possible? Need a valid explanation please.
On
you can also repeat the numbers
Wonder if that means $\,11,5+13,5+5=30\,$ (where the $\,,\,$ comma works as decimal separator).
On
Clearly impossible in base 10. Can it be done in another number base?
In base 5: $11+11+3=30$
Actually there are many other possibilities!
Another possibility: fill the boxes with $\binom{5}{3}$,15 and 5.
It holds that $\binom{5}{3}+15+5=30$ (base 10). Notice that $\binom{5}{3}=10$. I can't see any rule being violated as I'm using the 2 parenthesis in the list of valid symbols provided in addition to the numbers 5, 3, 15 and 5 and no extra symbol.
On
Do you have to fill in all three boxes? I would just put 15 in two of the boxes, e.g., $$\fbox{ } + \fbox{15} + \fbox{15} = 30,$$ and hope people understand the first box as being an implicit 0.
On
Change the base: $$11_9 + 11_9 + 11_9 = 10+10+10 = 30 \text{.}$$
Parentheses are in the list of usable box contents. Commas too. But you're upper limited to one pair of parens and to seven commas. $$(15+15,15)+15 = 30 \\ (15+15,15+15) = 30 \text{.}$$ Here, the parens represent the GCD.
Edit:
Change of base can also be made to work if number repetition were eliminated. $$ 11_{5} + 15_{7} + 13_{9} = 6 + 12 + 12 = 30 \text{.} $$
You have answered your own question: the sum of an odd number of odd numbers must be odd. Therefore it cannot equal 30.
You should not believe everything you read in a photo on the internet.