If $A : B = 2 : 3$, $B : C = 4 : 5$ and $C : D = 6 : 7$, what is $A : D$?

Explanation

1. 01

   $\frac{A}{D} = \frac{A}{B} \times \frac{B}{C} \times \frac{C}{D} = \frac{2}{3} \times \frac{4}{5} \times \frac{6}{7}$.

2. 02

   $= \frac{48}{105} = \frac{16}{35}$.

3. 03

   So $A : D = 16 : 35$.