2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/120969We obtain a formula which reduces the evaluation of a $_2ψ_2$ series to two $_2ϕ_1$ series. In some sense, this identity may be considered as a companion of Slater's formulas. We also find that a two-term ${}_2ψ_2$ summation formula due to Slater can be derived from a unilateral summation formula of Andrews by bilateral extension and parameter augmentation.13 pagesCombinatoricsClassical Analysis and ODEs33D15, 05A30text