step 1
Find out the slope of the given line
we have
y+1=-(1/2)x
The slope is m=-1/2
Remember that
If two lines are perpendicular
then
their slopes are negative reciprocal
so
The slope of the perpendicular line is
m=2
step 2
Find out the equation of the line in slope-intercept form
y=mx+b
we have
m=2
point (-8,7)
substitute and solve for b
7=2(-8)+b
7=-16+b
b=23
therefore
the equation of the line is
