Inductive subsets proof

Question

How could you solve this problem, You want to clasify all inductive subsets in $\mathbb{N}$ $$$$ (a) Show that for all A such that $\emptyset \not = A\subseteq \mathbb{N}$, A is inductive if and only if, there is an $n\in\mathbb{N}$ such that A={n,n+1,n+2,n+3...}.$$$$(b) (G1,$\preceq_1 $) be an ordered structure given by G1={A:A is an unductive subset of $\mathbb{N}$, with order $\preceq_1$ defined by A$\preceq_1$A', if and only if A$\subseteq$A'. Define (G2,$\preceq_2)$ as the ordered structure given by {0,1,$\frac{1}{2},\frac{1}{3},...,\frac{1}{n},...$}, where $\preceq_2$ is the usual $\leq$ in $\mathbb{R}$. Show that (G1,$\preceq_1 $) $\cong$(G2,$\preceq_2)$.