How to calculate price based on two attributes

Hi everyone,

I'm trying to set up a subscription to a magazine as a product where the price is based on a combination of attributes. It has two attributes

Term (1-year, 2-year, 3-year)
Location (US, Canada, Other Int'l)

The cost of the subscription changes based on a combo of these attributes. For instance, a US subscription costs $19, $38, $45 for 1,2, and 3 years. A Canadian subscription costs $24, $48, $55. As you can see, a Canadian subscription costs an additional $5, $10, and $15. This means I can't just set the two attributes independently (e.g. have location Canada add $5).

I really need a way for the price to be based the combination of attributes chosen. Any ideas on how to do this?

Thank you,
Kevin