Learn

We can use number operators on variables that hold number values:

``````\$tadpole_age = 7;
\$lily_age = 6;
\$age_difference = \$tadpole_age - \$lily_age;
echo \$age_difference; // Prints 1``````

Let’s look at another example of performing operations with number variables:

``````\$favorite_num = 22;
echo \$favorite_num + 1; // Prints 23
echo \$favorite_num; //Prints 22``````

In the code above, we created the variable `\$favorite_num` then we used `echo` to print that value plus 1. Note that we didn’t reassign the value of the `\$favorite_num` variable, so it still had the value 22 when we printed it on the last line.

We reassign number variables using the assignment operator:

``````\$age = 82;
echo \$age; // Prints: 82

\$age = \$age + 2;
echo \$age; // Prints: 84``````

Let’s do some addition and subtraction with variables!

### Instructions

1.

Can you help? I’m trying to figure out how much more I spent last month than this month. Last month I spent 1187.23 and this month I spent 1089.98. Create the variables `\$last_month` and `\$this_month` and assign them the corresponding numeric values.

2.

Use `echo` to print the difference between last month’s spending and this month’s.