LINUX OS - Do the following with a shell script / pico / cat

Write a shell/awk script, myaverage3, that reads in 3 numbers and then uses a self-defined function to compute the average. The average should be displayed in the main script, not inside the function you define. Please use the following testing cases to test your script:

$ ./myaverage3 3 4 8

The average is 5

$./myaverage4 -2 -9 -7

The average is -6

a) Please provide your script below (8 points):

b) The screenshot (2 points):