In the given mathematical puzzle find the missing number?

$8$	$13$
$16$	$6$
$4$	$19$
$22$	$2$
$?$	$32$

Hint: In such type of puzzles we are given the series of puzzles and can find the puzzles by
1. Firstly we take a quick look at the question
2. By developing develop a general idea regarding the theme of the problem
3. Then select the data that is giving you some concrete information out of total information given also select the data which helps in ruling out certain possibilities
In this puzzle we will identity the pattern of addition and subtraction the puzzle shows the alternate addition and subtraction of a number increasing in a pattern

Complete step-by-step answer:
STEP1: Given a puzzle is which first we will of serve the concept or the sequence of puzzle given puzzle is
STEP2: In the puzzle it shows
$8 + 5 = 13$
Here on adding $8$ into $5$ we get $13$
$16 - 10 = 6$
On subtracting $10$ from$16$ is equal to$6$
$4 + 15 = 19$
Here or adding $15$ in $4$ we get $19$
$22 - 20 = 2$
Here or on subtracting $20$ from $2$ on observing this we can say here is pattern which is forming by adding or subtracting alternatively multiple of $5$ on each step multiple of $5$ is getting increased and is added or subtracted alternatively in a pattern to pet the number
STEP3: In this we will $25$ will be added to get $32$ in the number let us assume this no to find be $x$
$x + 25 = 32$
On subtracting
$x = 32 - 25$
$x = 7$

Final answer is $7$

Note: In such patterns students mainly find it difficult to identify the pattern and they usually do not find the sequence used. They should use hit and trial on the first four sets hint and trial of addition subtraction multiplication and division.