Final answer:
To calculate the total charge for Mrs. Styles' 3-hour long party by the balloon artist, additional information on the balloon artist's base rate is required beyond the mentioned $35 additional supply fee for parties exceeding 10 children.
Step-by-step explanation:
The student's question concerned the extra charges applied by the balloon artist for parties with more than 10 children. Since there will be 12 children at Mrs. Styles' party, the balloon artist will indeed charge an additional supply fee of $35. However, the question does not provide the base rate that the balloon artist charges for a 3-hour party, only an additional fee. Without the base rate, we cannot calculate the total cost. Therefore, to answer how much the balloon artist will charge Mrs. Styles for a 3-hour long party, we need additional information about the artist's standard charges for a party of that length.