Answer
$$26.7 \mathrm{\ MeV}
$$
Work Step by Step
In Fig. $43-10,$
$Q_{1}=0.42 \mathrm{MeV}$,
$Q_{2}=1.02 \mathrm{MeV}$,
$Q_{3}=5.49 \mathrm{MeV}$
and
$Q_{4}=$ $12.86 \mathrm{MeV}$.
For the overall proton-proton cycle:
$$
\begin{aligned} Q &=2 Q_{1}+2 Q_{2}+2 Q_{3}+Q_{4} \\ &=2(0.42 \mathrm{MeV}+1.02 \mathrm{MeV}+5.49 \mathrm{MeV})+12.86 \mathrm{MeV}=26.7 \mathrm{MeV} \end{aligned}
$$
