If two lines are to stop them, their slopes are equal, therefore the slope of the line sought is -0.3.
We already have the slope and a point where the line passes.
Therefore we can find the equation of the line
y = -0.3x + b
5 = -0.3 (-1) + b
b = 5-0.3
b = 4.7
Then the equation of the line is:
y = -0.3x + 4.7.
Below is the graph of the line