About 1.83. You would set up the equation like this
The Slope is 0 (there is no incline or decline therefore there is no slope)
The slope point form is

m is the slope
x1, y1 are the coordinates of a point on the line
The slope of the line is -1
m = -1
point (-5, -4) lies on the line
x1 = -5 and y1 = -4
Let us substitute them in the form above

Remember (-)(-) = (+)

The equation of the line in the slope-point form is y + 4 = -1(x + 5)
Answer:
6 kg/m
Step-by-step explanation:
mass m = 3x^2.
rho ρ= dm/dx =6x
ρ(1) =6 Kg/m
linear density is the derivative of mass (m) with respect to position(x)
that is how fast is the mass changing at that position.