#!/bin/bash

# Subtracting and Adding Numbers
# Using variables

num1=23
num2=11
sum=0

# Note whitespace can make your script choke
# num1 = 23
# num2 = 11
# This will not run

### Subtracting Numbers ###
### Using expr & echo ###

# One way to do it:
expr $num1 - $num2

# Another way to do it:
echo $((num1 - num2))

### Adding Numbers and storing it in Sum ###

# One way to do it:
# As a command: 
(( sum=num1+num2 ))
echo $sum

# As a substitution:
sum=$((num1 + num2))
echo $sum