y=m1x+am1......(i)y=m2x+am2
Substituting y from (i), we get
m2x+am2=m1x+am1(m2−m1)x=a(1m1−1m2)(m2−m1)x=a(m2−m1m1m2)⇒x=am1m2y=m2(am1m2)+am2y=a(1m1+1m2)
So the point of intersection is (am1m2,a(1m1+1m2))