It seems that part of the question was cut off. Please edit and repost. Anyway, it looks like you want the total number of cell phone users N years after 1992, assuming a growth rate of 26% per year.
If you start with 17 x 106 in 1992, then N years after 1992 you will have
Total = (17 x 106) (1.26)N
After 5 years, total = (17 million)(1.26)^5 = 54.0 million (rounded off). That is the total for 1997.