But we know from our statements above, that each of the integers can be stated in terms of the others, which means that b = something*a. c = something*b; therefore, even c can be expressed in terms of a. We know that they're even, which means that each number is offset by 2 in sequence. If they were regular consecutive integers, we could just add +1, instead.
This part seemed a little confusing to me with the formula before it looks like it's handled differently, but I appreciate the help that second question gave me the worst headache ever.