A printer wants to center a 6 in wide column of text a page that is 8.5 in wide if the margins on the two sides are even how wide should each margin be

Question

The answer is like combining like terms 

Answer 1

subtract 6 from the overall width; you have 2.5 inches to serve as two (combined) margins.

if they're to be equal margins, the half of 2.5 inches is 1.25 inches per margin.