Solution
= Solution
Belinda remains in one <inertial frame> with $v=5c/13$, so the <time dilation> factor is $\sqrt{1-v^2/c^2}=12/13$. Her elapsed <proper time> is
$$
\boxed{\tau_B=\frac{12}{13}T=\frac{204}{35}\,\mathrm{yr}\simeq5.8286\,\mathrm{yr}.}
$$
The reunion event is shared by both twins, making their clock readings directly comparable without any convention for synchronizing separated moving clocks.