The following expression determines the total average credit card debt:
c = 407t + 5960
due to t is considered from 1995, then, for this year t = 0 and for the year 2000 t = 5.
Replace t = 5 into the expression for c and simplify:
c = 407(5) + 5960
c = 2035 + 5960
c = 7995
Hence, for year 2000, the total average credit card debt is $7995.