Two waves that set up a standing wave in a long string are given by the wave

Question:

Two waves that set up a standing wave in a long string are given by the wave functions
y1 = A sin (kx ─ wt + ǿ)
and
y2 = A sin(kx + wt)
Show (a) that the addition of the arbitrary phase constant ǿ changes only the position of the nodes and, in particular,
(b) That the distance between nodes is still one half the wavelengths.