In the Shell scritpt Arithmetic Lab facing the issue

Shell Scripting
#1

In the Shell script, Arithmetic Lab question no.5 faces the below issue
After following the same step I am getting the error of FIle - is unavailable.

root@caleston-lp10:/home/bob# ./calculate-average.sh 1 2 1
4
File - is unavailable.

root@caleston-lp10:/home/bob#

#2

Please paste your script

as a code block

to help us tell you where you went wrong.

#4

Now the script is working. Yesterday maybe some issue was there in the lab. Thanks

num1=$1
num2=$2
num3=$3
sum=$(( num1 + num2 + num3 ))
average=$(echo “$sum / 3” | bc -l)
echo $average