VB Trying To Make Sense Of Homework?

So my teacher gave us this assignment that I'm having trouble understanding why she wants us to write outside of the button Private Sub.1. Write the code for the Calculate Total and Grand Total button a. Declare a variable to accumulate the individual totals outside the sub procedures b. Calculate the total by multiplying the selected number of atendees by the selected cost, and display this total in the label next to Total c. Calculate the grand total by adding the total calculated in step 3.b to the grand total variable. Display the grand total next to Grand Total I'm don't understand why she says 1a. I feel like you can just write all the variables in the same Sub on the calculate button.