Answer:
x = -3
Explanation:
A line has equation: y = ax + b
This line has slope a = 1
This line passes (4, 1)
=> 1 = 4 + b
=> b = -3
=> The equation of this line : y = x - 3
This line passes another point (x, -6)
=> -6 = x - 3
=> x = -6 + 3
=> x = -3