Let ${P_1}:\overrightarrow r \,.\,\left( {2\widehat i + \widehat j - 3\widehat k} \right) = 4$ be a plane. Let P₂ be another plane which passes through the points (2, $-$3, 2), (2, $-$2, $-$3) and (1, $-$4, 2). If the direction ratios of the line of intersection of P₁ and P₂ be 16, $\alpha$, $\beta$, then the value of $\alpha$ + $\beta$ is equal to ________________.