I wonder if you've asked the question properly. You state that the slope of the line is -1/2. That was the question you asked.
If you meant to ask "What is the equation for a line . . .", then read on. . . . .
The form of an equation of a straight line is often stated as y = mx + b, where m is the slope and b is the y intercept (the value of y when x is equal to 0).
Given the slope of -1/2, we can write:
y = -(1/2)x + b
To find b, use the point that is provided (-6,-5) and substitute t6he x and y and solve for b.
-5 = -(1/2)*(-6) + b
-5 = 3 + b
b = -8
The equation becomes y = -(1/2)x - 8