Question

The scale on a map is 1cm:12km. Find the actual distance in km for 7.25 cm.

Answer 1

1 cm : 12 km 
so, if you have 4cm (that's 1 * 4) you can find the real distance by multiplying 12 * 4 = 48 km 

The same can be done for 7.25 (1 * 7.25) now you do 12 * 7.25 = 87 km 

Now the same for 11.25 
12 * 11.25 = 135 km