Question 1003874


 compare the line {{{y=8x-9}}} to {{{y=mx+b}}} where {{{m}}} is a slope and {{{b}}} is y-intercept

so, the line {{{y=8x-9}}} has  a slope {{{m=8}}}

by definition, the slope of a line {{{parallel}}} to this line will be same, {{{m=8}}} 

by definition, the slopes of {{{perpendicular}}} lines  are negative reciprocals to each other; so,{{{m=-1/8}}}