first off, what's the slope of "r" anyway,

.
low and behold, since "r" is in slope-intercept form, notice, it has a slope of -1/2.
now, any line perpendicular to "r", will have a
negative reciprocal slope to it, that is,

so we're really looking for a line whose slope is 2, and runs through 4,-3,
![\bf \begin{array}{ccccccccc} &&x_1&&y_1\\ % (a,b) &&(~{{ 4}} &,&{{ -3}}~) \end{array} \\\\\\ % slope = m slope = {{ m}}\implies 2 \\\\\\ % point-slope intercept \stackrel{\textit{point-slope form}}{y-{{ y_1}}={{ m}}(x-{{ x_1}})}\implies y-(-3)=2(x-4)\implies y+3=2x-8 \\\\\\ y=2x-11]()