Customers don't know math

I once had a woman call me up with questions. She was buying a large package for a group shot and wanted to know how many sheets of photos each family would get. She was asking about our different packages.

"Now our silver package will give you twelve sheets"

"Ok," she said, "so if I have five families, how many sheets would each family get"
It was like I was talking to a fourth grade division problem. "Well" I said "On average each family is going to get about two and a half sheets"

"How can you have half a picture?"

"Well, you can't. It's an average. Everyone will get two and you'll have some extras."

"Extras?"

"Yes, because in total you have twelve sheets and if everyone has two sheets, then you'll have two extras."

"So how many do each get?"

I had to go on to repeat myself a number of times. I tried to keep it as flexible as possible for her, to show her how she could do different numbers for each family (which is what she wanted) but in the end had to just tell her "Each family gets two sheets and your grandmother gets four"

Now, I can [almost] understand how it could be somewhat confusing for someone around thirty years old when you have remainders and want a whole number. But later...

"Ok so now instead of that collection," I said "you could go with the gold which I could mix around to give you 20 sheets"
"So if I have five families for that shot, how many sheets would they each get?"
"Well, if I divide 20 by 5, I get 4 each."
"What if I had twenty five sheets with the other collection?"
"You would have 5 each."
"Ohhhh okay"