Answer:
m = 11
Step-by-step explanation:
Since the points are collinear then the slope between points are equal.
Calculate the slope m using the slope formula
m = ( y₂ - y₁ ) / ( x₂ - x₁ )
with (x₁, y₁ ) = (5, 1) and (x₂, y₂ ) = (1, - 1)
m =
=
= 
Repeat with
(x₁, y₁ ) = (1, - 1) and (x₂, y₂ ) = (m, 4)
m =
=
= 
Cross- multiply
m - 1 = 10 ( add 1 to both sides )
m = 11