Pattern Recognition Puzzle

Question

I would like some help explaining the pattern on this puzzle. It is from a game on my phone and I can only use a number pad to answer. There are no negative signs.

Puzzle:

8    13 
16   6
4    19
22   2
?    32

I noticed it decreases by two and increases by three in a zigzag manner but I do not see how it helps me determine the "?".

Through guessing I found the number to be 7, but I cannot explain it. Any input would be appreciated. Thank you.

Answer 1

The differences are 5,10,15,20,25 with the smaller number on the left, right, left, right, left.

Answer 2

The answer is $42$ of course, and the function is:

$$f(x)=\frac{839x^4}{7814016}-\frac{2075x^3}{279072}+\frac{55855x^2}{279072}-\frac{91127x}{28728}+\frac{84112}{2907}$$

Answer 3

i know the game :) 42 not working ;)

7 is right.. 8 + 1*5 = 13 (first row) 16 - 2*5 = 6 (second row) 4 + 3*5 = 19 (3rd row) 22 - 4*5 = 2 (4th ...) 7 + 5*5 = 32 (5th row... and so on, +/- x*5)