Mavis Marble uses her new Mitra Card ( the card that does the math for you ) to buy material and yarn. She has been
using it for 4 months. She just got a letter in the mail saying
her account is now at -355.
can't be. My card says I have a credit of $240."
Mavis will need
to compare her Mitra card charges with her payments.
Find the correct
balance for her Mitra account.