# How do you find the distance between Riverside and Milton if they are 12 cm apart on a map with a scale of 4 cm :21 km?

Nov 10, 2016

$21 \text{ km." xx (100,000" cm.")/(1" km.") = 2,100,000" cm.}$

So, the scale of the map is 4 cm: 2,100,000 km.

Now that we're in equivalent units, we can set up a proportion.

$\frac{12}{x} = \frac{4}{2 , 100 , 000}$

$x = \frac{2 , 100 , 000 \times 12}{4}$

$x = 6 , 300 , 000 \text{ cm.}$

Let's finally convert back to kilometres.

$6 , 300 , 000 \text{ cm." xx (1" km.")/(100,000" cm.") = 63" km.}$

Hence, the actual distance between Riverside and Milton is $63$ kilometres.

Hopefully this helps!