Answer:
To me a two column proof is usually associated with Euclidean Geometry.
To use it here in this rather simplistic problem is like using a sledge hammer to drive in a finishing nail ...
here is what I would do
7y=8x-14; y=6
then:
42 = 8x - 14
56 = 8x
x = 56/8 = 7
There! I have proven it.
Explanation:
