Suppose a Country's Population at Any Time T Grows in Accordance

Suppose a country's population at any time t grows in accordance with the rule
​ ​
where P denotes the population at any time t, k is a positive constant reflecting the natural growth rate of the population, and i is a constant giving the (constant) rate of immigration into the country. If the total population of the country at time t = 0 is P​₀, find an expression for the population at any time t.