what is the equation of a line that passes through the point (1, 8) and is perpendicular to the line whose equation is y=x/2+3 ?

Perpendicular lines have slopes that multiply to -1

y=mx+b
m=slope
given y=x/2+3
y=(1/2)x+3
slope is 1/2

1/2 times what=-1?
what=-2

so

y=-2x+b
and passes through(1,8)
x=1 and y=8
8=-2(1)+b
8=-2+b
10=b

equatino is y=-2x+10

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