  We solve the two Diophantine equations $P_k=J_n+J_m$ and $Q_k=J_n+J_m$ where
$\left\lbrace P_{k}\right\rbrace_{k\geq0}$, $\left\lbrace
Q_{k}\right\rbrace_{k\geq0}$ and $\left\lbrace J_{k}\right\rbrace_{k\geq0}$ are
the sequences of Pell numbers, Pell-Lucas numbers and Jacobsthal numbers,
respectively. The main tool is the theory of linear forms in logarithms.
