no question is being asked... 'e' would appear to be the numeric constant approximated by 2.72 but that should be specified because it will more typically indicate and exponent, as in '22.9e10' for "22.9 * 10^10"

if you need to find the population for some specific year after 2005, the solve the equation with 't' substituted by '2005-t', making certain that 't>2005'