Line and Plane Intersection

Let the line ‌

x−3

7

=‌

y−2

−1

=‌

z−3

−4

intersect the plane containing the lines ‌

x−4

1

=‌

y+1

−2

=‌

z

1

and 4ax−y+5z−7a=0=2x−5y−z−3,a∈ℝ at the point P(α,β,γ). Then the value of α+β+γ equals ________.