Use the associative law of addition to write an equivalent expression for (x+2)+y
x + (2 + y)
http://www.mathsisfun.com/definitions/associative-law.html
The associative law of addition states that changing the grouping of numbers being added does not change the sum.
To apply the associative law of addition to the expression (x+2)+y, we can group the numbers differently. Let's group x and y first, and then add 2 to the result.
So, (x+2)+y is equivalent to x+(2+y).
By applying the associative law of addition, we have now written an equivalent expression.