The average of all data values is called the mean, and can be found by adding all the values together then dividing the sum by the number of values.
Example: If the data values were 7, 3, 4, and 6, you'd add them all together:
7+3+4+6=20
then divide by the number of values
there are four values, so we divide the sum by 4
20/4=5 so in this case the mean would be five.