Multiple-Sheet Workbook Management

[n03c03]

Hey everyone Ive been working hard on this homework and I can't figure out step 12.
STEP 12:Enter a 3-D formula in cell C3 on the October worksheet that calculates the overall percentage of total Sunday Orchestra Front tickets sold based on the total available Orchestra Front seating. The 3-D formula must perform several internal calculations, avoid raw numbers, and use an appropriate mix of relative and mixed references to derive the correct percentage. Format the result with Percent Style. The result is 100%, based on the sum of the Sunday Orchestra Front tickets sold divided by the total available tickets for all four weeks. Copy the formula to the remaining cells in the range C3:G6.

What i'm having problem is how to calculate the percentage. I have always had problem with converting anything to percentage. I try to look for a formula but i'm not having any luck. Can some one help me please.