If $\frac{2a + b}{a + 4b} = 3$, then find the value of $\frac{a + b}{a + 2b}$
[A] $\frac{10}{7}$
[B] $\frac{10}{9}$
[C] $\frac{5}{9}$
[D] $\frac{2}{7}$