Slope intercept form:
y= mx +b
Where:
m= slope
b= y-intercept
For: y= -2x+1, slope = -2
Parallel lines have equal slopes, so m= -2
So far we have:
y= -2x + b
Replace (x,y) by the given point (-5,-2) and solve for b:
-2 = -2 (-5) + b
-2 = 10 + b
-2 - 10 = b
b = -12
Final equation:
y= -2x- 12