I need help. I don't understand.

2. The rate of change of bears, N, in a population is directly proportional to 350 - N , Time, 1, is measured in years. When ?=0, the population is 100 and when ? = 2, the population has increased to 250. a.) Write and solve a differential equation that describes this Situation. b.) Find the bear population in 3 years. c.) Find lim N(t)