Explanation:
Addition is a mathematical operation that represents combining
collections of objects together into a larger collection. It is signified by
the plus sign (+). For example, in the
picture on the right, there are 3 + 2 apples-meaning three apples and two other
apples-which is the same as five apples. Therefore, 3 + 2 = 5 (Our solved example in mathguru.com uses this concept)
Besides
counting fruits, addition can also represent combining other physical and
abstract quantities using different kinds of numbers: negative numbers, fractions, irrational numbers, vectors, decimals and more.
3 + 2 = 5 with apples
http://en.wikipedia.org/wiki/Addition
In mathematics, a variable is a value that may change within the
scope of a given problem or set of operations. (Our solved example in mathguru.com uses this concept)
http://en.wikipedia.org/wiki/Variable_(mathematics)
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.