Show me how to change 80 miles into kilometers

Many sites on the internet can automatically convert miles to kilometers. However, learning how to do it on your own is a good idea if you ever don't have an internet connection. The most important thing to remember is that there are 1.6 kilometers in a mile. This means that you can multiply your number of miles by 1.6 to get kilometers.

For example 50 mile 
Write out 50 mile
1 mile = 1.6 kilometers 
so you multiply by 1.6 kilometers 
which you will get 80 kilometers 
But 1.6 isn't exactly precise if you want to make it precise multiply by 1.60934
which will equal to 80.4673 kilometers

The distance between them is 4.0
The equation would be 1.5-(-2.5)=d

Hope that helps?