What is one possible disadvantage of hearing the characters’ voices as opposed to silently reading the scene?

Jess wanted to save money to buy a new outfit. jess saved $27.40 in june, $28.90 in july and $21.10 in august. however, she also had to spend $21.60 on school supplies and $45.10 on her dog. if the outfit costs $106.80, how much money does jess still need to save