Question 684323
 first find a line that passes through given point ({{{8}}},{{{12}}})and has slope {{{m=3.9}}}

*[invoke find_line_by_slope_and_point 8, 12, 3.9]

now we can find the slope of a line perpendicular to a line {{{y=3.9x-19.2}}} which passes through given points

perpendicular line has a slope {{{-1/3.9=-0.26}}}


*[invoke find_line_by_slope_and_point 8, 12, -0.26]


{{{y=-0.26x-14.08}}}


{{{ graph( 600, 600, -10, 10, -30, 10, 3.9x-19.2, -0.26x-14.08) }}}