A mail-order company charges $4 for shipping orders of less than $50, $6 for orders from $50- $200, and $8 for orders over $200. One day the total shipping charges were $2160 for 384 orders. Find the number of orders shipped at each rate if the number of orders under $50 is 12 more than twice the number of orders over $200.
I know how to do determinants but just having a hard time figuring out the equations I should be using. Any help would be appreciated. Thank you