What is the value of k

y = f(x)
y = slope x + y intercept
y intercept = - 3
slope = -3/-1.5 = 2
Equation
f(x) = 2x - 3
y = g(x)
y = slope*x + y_intercept
The y intercept = 6
The slope I'd better do the long way.
Take two points on g(x)
(1.5,0) and (0,6)
y1 = 0
y2 =6
x1 = 1.5
x2 = 0
m = (6 - 0)/(0 - 1.5)
m = 6 / - 1.5
m = - 4
The equation of the line is
g(x) = - 4x + 6
g(x) = - 2(2x - 3)
g(x) = -2 * f(x)
Answer: k = - 2