The correct equation is P(t) = Po*e^(kt). Please enclose "kt" inside parentheses and use the " ^ " symbol to indicate exponentiation.
"k" is the growth constant, which here is 0.017. "t" is the number of yeasrs. P(7) is the population after 7 years. Po is the initial population, which in this case is 91 million.
The initial value, when t = 0, is 91 million.
After 7 years, the population, P(7), was P(7) = (91 million)*e^(0.017*7). This evaluates to P(7) = (91 million)*(1.070) = 96 million