Solution:
The number of hours worked for the month is

The amount earned as a tutor for one hour is

The amount earned as a waitress for one hour is

The number of hours Rachel worked as a tutor is

Let the number of hours she worked as a waitress be

The equation representing the total hours worked for the month will be

The amount of money Rachel earned as a tutor this month will be calculated as

The amount of money Rachel earned as a waitress this month will be calculated as

The expression to represent the combined total earned this month will be

Substitute equation (1) in equation (2) above, we will have

Hence,
The expression for the combined total she earned this month = 1365 -6t