Thank you for your reply. I've been studying what you've posted for a bit, and have tried applying it.
k=.693/22 years = .0315 for the decay constant, and use your first equation to multiply .0315 by 2.65x1021 to get 8.3x1019.
According to the textbook, the answer for this should be 2.6x1012. The activity in curies is supposed to be 71 curies.
I've tried this problem for a while now, and still can't come up with the answers from the textbook