Explanation:

Distance is a numerical description of how far apart objects are. In physics or everyday discussion, distance may refer to a physical length, or estimation based on other criteria (e.g. "two counties over"). (Our solved example in mathguru.com uses this concept)

In most cases, "distance from A to B" is interchangeable with "distance between B and A".

http://en.wikipedia.org/wiki/Distance

Addition is a mathematical operation that represents combining collections of objects together into a larger collection. It is signified by the plus sign (+). (Our solved example in mathguru.com uses this concept)

For example, if there are 3 + 2 apples-meaning three apples and two other apples-which is the same as five apples. Therefore, 3 + 2 = 5. 

The plus sign

Addition is written using the plus sign "+" between the terms; that is, in infix notation. The result is expressed with an equals sign. For example,

1 + 1 = 2 (verbally, "one plus one is equal to two")

2 + 2 = 4 (verbally, "two plus two is equal to four") (Our solved example in mathguru.com uses this concept)

http://en.wikipedia.org/wiki/Addition

The above explanation is copied from Wikipedia, the free encyclopedia and is remixed as allowed under the Creative Commons Attribution- ShareAlike 3.0 Unported License.