$Q = \{ x \in \mathbb{N} \mid 2x > 15 \}$

$R = \{ x \in \mathbb{N} \mid 1/4x > 15 \}$

$S = \{ x \mid x \in \mathbb{Z}, -1/4 \le x \le 12 \}$

$T = \{ x \mid x \in \mathbb{N}, 2x - 4 = x + 10 \}$

$V = \{ x \in \mathbb{N} \mid -2x = 12 \}$

$W = \{ 2^{a-b} \mid 2a - 2 = b \}$

$X = \{ x^2 - y \mid x, y \in \mathbb{N}, x + y < 3 \}$

$Y = \{ x^y \mid x, y \in \mathbb{Z}, xy = 4 \}$

$Z = \{ (-1/4)^x \mid x \in \mathbb{N}, 2x \le 12 \}$

$M = \{ 2^{x+y} \mid x, y \in \mathbb{N}, xy = 4 \}$