$\"\"$

Mean of a set is the sum of the values divided by the number of values in the set.

Mean of two real numbers is, $\"\"$ , where a, b are real numbers.

$\"\"$ (Substitute $\"\"$ )

$\"\"$ (Add: $\"\"$ )

$\"\"$ (Divide: $\"\"$ ) $\"\"$

Mean of 5, $\"\"$ is $\"\"$ .