Answer
a) Out of phase.
b) See the table below.
Work Step by Step
a) We can see, from the given figure, that the waves of the two sources are not at the same distance from their source at the same time interval.
Thus, they are out of phase.
b) From the given graph, we can find $r_1 $ for each point which is the distance from the first source, $r_2$ which is the distance from the second source, $\Delta r=|r_2-r_1|$ which is the path length difference, $\rm C$ or $\rm D$ which is constructive or destructive.
Noting that the two sources are emitting the same wavelength $\lambda$ since the distances between the circles around both of them are equal, but it seems that the second source is dealing by half wavelength.
\begin{array}{|c|c|c|c|}
\hline
\rm points&r_1 &r_2& \Delta r&\rm C/D\\
\hline
\rm P& 2\lambda & 3\lambda&\lambda& \rm D\\
\hline
\rm Q & 3\lambda & 1.5\lambda &1.5\lambda&\rm C\\
\hline
\rm R& 2.5\lambda & 3\lambda&0.5\lambda&\rm C \\
\hline
\end{array}