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i am going to guess 18.

My answer: 18, but i see 22 quiet possible too :P

I honestly have no clue.

congrats @misterd21 @scrazy @lig007 for guessing correct ..... :)
nice attempt to @billynoe79 @avarice @iggy85 better luck next time... :)

What is the correct rationale for this puzzle?

3x4=12->+3=15
7x5=35->+3=38
3x5=15->+3=18

I was on the right track but messed up the numbers

hmmm it happens :)