Let intercept on y axis (0,a) on x axis (b,0).
we must be knowing that slope of line is given by m=[y-p]/[x-q] at (q,p) and m=[y-k]/[x-l ] at [l,k]
By equating m on both sides we have
Interpreting the intercepts (0,a)=(q,p) and (b,0)=(l,k)
we have [y-a]/x=y/[x-b]
on simplifing this we get the equation of line y= (-a/b)x+a
Geometrically this signifies slope of line m=(-a/b) and the above intecepts.