3.2.14 Lines on a plane

condition: In a rectangular coordinate system on a plane, the sides \( A B \) and \( B C \) of the triangle \( A B C \) lie on the lines \( x-2 y+18=0 \) and \( x-y-1=0 \) respectively. The altitudes of the triangle intersect at the point \( H(1 ; 2) \). Find the coordinates of the vertex \(A\).