# Using expr for math.
# Calculates sales tax.

echo -n "Please enter the amount of purchase: "
read amount
echo

echo -n "Please enter the total sales tax: "
read rate
echo

tax_base=`expr $amount \* $rate`


tax=`expr $tax_base / 100`

total=`expr $amount + $tax`

result=$total

echo "The total with sales tax is: \$ $result."
When you run this script, you'll see:
$ sh exercise_09_03
Please enter the amount of purchase: 107
 
Please enter the total sales tax: 7
 
The total with sales tax is: $ 114.
Compare this with the math2 script:
$ sh math2
Please enter the amount of purchase: 107
 
Please enter the total sales tax: 7
 
The total with sales tax is: $ 114.49.