Also, I'm going to cheat and use a cake mix so does anyone know how many mixes I will need for the same size cake?
According to the Wilton chart, you need 6 cups of batter for a 10"x10"x2" pan. Therefore, 3 cups would be needed.
Someone else correct me if I'm wrong, but doesn't a cake box mix make 5-7 cups? Therefore, she would only need a half box?
Cake mix makes 4-6 cups depending on the brand and flavor. Betty and Phils usually are 4-5 and Ducan is 5-6.
By the way it isn't cheating to use cake mixes.
Any time you need to know how much batter to put in a pan, just measure cups of water into the pan to get it 2/3 full, then dump out the water.