The easiest way to do this is to pick any number to substitute in for the variable <em>k </em>for ALL of the expressions, and find the expressions that equal the same as the first expression being compared.
For example, lets just make <em>k </em>equal 1 to make things easy. Plug 1 into <em>k</em> into the first expression. 2k + 2 + k + 3 + 2k → 2(1) + 2 + (1) + 3 + 2(1) = 10.
Now we do the same to the rest of the expressions and see which ones ALSO equal 10.
