slope m of the line = 5-4 / 2-4 = -1/2
using the point slope form of a line:-
y - y1 = m(x - x1) where (x1,y1) is a point on the line, we have:-
y - 5 = -1/2(x -2) using the point (2,5)
multiply through by 2:-
2y - 10 = -x + 2
x + 2y = 12 is the answer