equation of a line that passes through the point (x1,y1) and has a slope of m is
y-y1=m(x-x1)
given
(1,-2) and slope of 1/3
y-(-2)=1/3(x-1)
general form is ax+by=c (or ax+by+c=0) where a,b,c are integers and a is positive
y-(-2)=1/3(x-1)
y+2=1/3(x-1)
times both sides by 3
3y+6=x-1
minus 3y both sides
6=x-3y-1
add 1 both sides
7=x-3y
x-3y=7
To get ax+by+c=0 form, subtract 7 from both sides to get
x-3y-7=0
