以下是Simon and Blumes (1994)的Leslie Population Model and Difference Equations问题，请大家帮帮忙解答一下，谢谢。
1. The intuition behind the Leslie Population model.
"Consider the organism that lives for two years. Let b1 be the birth rate of indivdiuals in their first year and b2 the birth rate for individuals in their second year. Let d1 denote the death rate of first-year individuals, so that (1 - d1) of the first-year indivdiuals survive to year two. Let xn and yn denote the number of first-year individuals and second-year indiivduals, respectively, in year n. The dynamics over time of this populationm are described by the system of diffrence equations
xn+1 = b1xn + b2yn
yn+1 = (1 - d1) x n
可不可以帮我把以上的Model用文字（中文英文均可）解析一下呢？ 我不大懂the intuition behind the model.
2. Consider the coupled system of difference equations generated by a Leslie model with

(1)
The next step given i nthe textbook is:
The right change of coordinates for solving this system is
X = (1/6)x + (1/3)y
Y = (-1/6)x + (2/3)y (2)
可不可以解析一下Simon and Blumes是怎么从Step (1)到Step (2)呢？ 预先谢谢了。