(a)
\( y = \frac{1}{2}|x|: \text{ upward} \)
\( y = \frac{2}{3}|x|: \text{ upward} \)
\( y = 2|x|: \text{ upward} \)
\( y = -4|x|: \text{ downward} \)
(b) The equation with the widest graph is \( y = \frac{1}{2}|x| \).
(c) The equation with the narrowest graph is \( y = -4|x| \).