Question

Let S = [a belongs to N ; a = 4x + 10y; x; y belong to Z]. Are all elements of S positive?

Answer 1

This makes no sense to me, sorry.

Answer 2

If \(S\) is comprised of all \(a\) that are in the set of natural numbers \(\mathbb{N}\) that satisfy \(a=4x+10y\), then surely \(S\subseteq\mathbb{N}\).