Final answer:
Tessa's account balance went from $90 to $15 after paying her bills and depositing money from her part-time job.
Step-by-step explanation:
Tessa's starting balance is $90.
She pays her cable/internet bill of $60, so her account balance decreases to $90 - $60 = $30.
Then, she deposits $50 from her part-time job, so her account balance increases to $30 + $50 = $80.
Finally, she writes a check for $65 to pay her credit card bill, so her account balance decreases to $80 - $65 = $15.
Therefore, Tessa's final account balance is $15.