Matrices and Determinants: JEE Main 2020 Mathematics question

If for some $\alpha$ and $\beta$ in R, the intersection of the following three places x + 4y – 2z = 1 x + 7y – 5z = b x + 5y + $\alpha$z = 5 is a line in R³, then $\alpha$ + $\beta$ is equal to :