linux - Averaging lines without awk using bash -

i'm starting use bash, , i'm having difficulties bash arithmetic. lets have cities 3 temperatures, , i'd average temperatures without using awk command. how can this? i've done awk, i'm practicing different techniques.

# citytemp.txt 4 cities, 3 day's temperatures toronto 20 25 30 miami 80 80 110 london 40 20 60 new york 5 10 15  

lets i'm trying write script output:

25 toronto 90 miami 40 london 10 new york 

i've done piping , awk command, i'm having problems doing without using awk.

again, i'm new this. tried loop, didn't know doing.

---edit 1:

benjamin w. i'm editing again, right i'm playing loop:

#!/bin/bash  in $(cat $1)     echo "i is: ${i}" done < $1 

this is, maybe obviously, printing every field citytemp.txt 1 @ time.

---edit 2:

this ending attempt

while read -a rows     total=0     sum=0     in "${rows[@]}"             sum=`expr $sum + $i`         total=`expr $total + 1`     done     average=`expr $sum / $total`     output = ${average} done < $1 echo ${averages} 

this should work in posix shell, may shebang #!/bin/sh.

#!/bin/sh  avg () {   city=   while [ $# -gt 3 ];     city="$city $1"     shift   done   echo $((($1 + $2 + $3) / 3)) $city }  while read line;   avg $line done < citytemp.txt 

this have been lot easier if city last on each line, lol.