Explanation:
Total earnings = (Hours as a tutor * Tutor hourly rate) + (Hours as a waitress * Waitress hourly rate)
Let:
t be the number of hours Charmaine worked as a tutor.
w be the number of hours Charmaine worked as a waitress.
Tutor hourly rate = $10 per hour.
Waitress hourly rate = $13 per hour.
So, the expression for Charmaine's combined total earnings this month would be:
Total earnings = (t * $10) + (w * $13)
However, you're given that Charmaine worked a combined total of 107 hours at her two jobs this month, so you can also express w in terms of t:
w = 107 - t
Now, substitute this expression for w back into the total earnings equation:
Total earnings = (t * $10) + ((107 - t) * $13)
Simplify:
Total earnings = $10t + $1,391 - $13t
Now, you can simplify further:
Total earnings = $1,391 - $3t
So, the expression for the combined total dollar amount Charmaine earned this month is:
Total earnings = $1,391 - $3t