Data Sufficiency

paml wrote:Can anyone recommend similar problems (preferably from one of the Official Guides) to this one that I can practice with?

Here's a nice one (not written by me):

One night before a show, each member of Iggy's band drank an 8-ounce mixture of rum and coke. While the actual amount of rum and coke in each member's 8-ounce drink varied, all the drinks had some rum, some coke, and nothing else. If Iggy's drink had one fourth of the rum and one sixth of the coke, how many people are in Iggy's band?

A:: 4
B:: 5
C:: 6
D:: 7
E:: Cannot be determined from the information given

Thanks Matt! I can't seem to figure that question out - my best guess is E.
The equations I've set up are:
Total liquid = 8X, with X being the # of ppl in the band.
R+C = 8X, with R being the total amount of rum, and C being the total amount of coke.
R/4 + C/6 = 8; this is the amount in Iggy's drink.
But there are only 2 equations with 3 unknowns so I can't seem to solve for X.