Question

some friends participated in a pull - up contest.
doing pull - ups
how many participants did at least 1 pull - up?
participants

Explanation:

Step1: Count the number of X's for each value from 1 to 5

For value 1: 2 X's.
For value 2: 9 X's.
For value 3: 0 X's.
For value 4: 3 X's.
For value 5: 6 X's.

Step2: Sum up the counts

$$2 + 9+0 + 3+6$$
$$= (2 + 9)+(3 + 6)$$
$$= 11+9$$
$$= 20$$

Answer:

20