6.In a model of a ship, the mast is 9 cm high, while the mast of the actual ship is 12 m high. If the length of the ship is 28 m, how long is the model ship?
$$\frac{9}{12}=\frac{x}{28}$$
$$\Rightarrow x=28\times \frac{9}{12}$$
$$\Rightarrow x=21 cm$$