I'm not 100% certain if this is the correct forum so please forgive me if it is better suited in another location but I am not certain exactly what kind of math would be involved in solving this issue and this forum seemed like the best fit.

Problem: Figure out how much of a specific product each guest will use, broken down by adults and kids.

Data: We have the total usage of a product, the number of adults, the number of kids, broken down by week.

Example:

Week 1: 1340 Adults and 627 Kids consumed 13.5 units of product x.

Week 2: 1278 Adults and 593 Kids consumed 14.8 units of product x.

From this data we can easily conclude how much of product x the average guest uses if we don't break down the guest count by adults and kids. However, I'm stuck trying to calculate the usage broken down by Kids and Adults. I've tried solving this using a system of equations and while I arrived at a mathematically correct solution it was obviously wrong from a logical standpoint (one of the variables ended up negative which would indicate that a guest was giving the business a certain amount of product x).

With the data I have is it even possible to calculate this? If so what method would be best suited to solving this type of problem. If this isn't possible what additional data would I need to be able to calculate this?

Thanks.