Rearrange the equation into slope intercept form
7x+3y=18
3y=-7x+18
y=-7x/3+18/3 so the slope of the reference line is -7/3
To be perpendicular to this line the slope must be the negative reciprocal of this...mathematically m1*m2=-1. So the slope of our perpendicular line is:
-7m/3=-1
-7m=-3
m=3/7 so our line so far is:
y=3x/7+b, using point (6,8) we can solve for b, the y-intercept
8=3(6)/7+b
8=18/7+b
56/7-18/7=b
38/7=b so our line is:
y=3x/7+38/7 or if you prefer
y=(3x+38)/7
