this is actually really easy if you just look at it ...... Ok so if 2 + 3 = 10 but its suppost to be 5 , so you added 5 more ... Next problem , 5 + 2 = 12 but its suppost to be 7 , then you added 5 more ... Next problem , 7 + 5 + 17 but its suppost to be 12 , so you added 5 . you see a pattern well im going to keep on going ... Next problem , 9 + 8 = 22 but its suppost to be 17 , so you added 5 ... ok so 3 + 5 we all know thats 8 right ? well since throughout all these problems its been 5 more, just add 5 more to this one witch makes it into 13 ... and yes 13 is your answer