This problem is an example of ratio and proportion. A ratio is a comparison between two different things. You are given the equivalent distance of a 1 2/5 kilometers to 1 mile. Also you are given 4 miles. You are required to find the distance in kilometers of 4 miles. The solution of this problem is,
1 2/5 kilometers /1 mile = distance/ 4 miles
distance = (4 miles) (1 2/5 kilometers /1 mile)
distance = 28/5 or 5.6 kilometers
There are 5.6 kilometers in 4 miles.