Theorem 6. Let B be the size of the box obtained in Theorem 5, if B + b d > a d, then any box of size B + 2b dcontains a solution of (1.1).Proof. We are to find maximum enlargement of the box in Theorem 5 not containing a solution. Let (x , y) the corner of the box on Lk+d inTheorem5. Since B + b d > a d,thenthereisasolution (x0 , y0) on Lk+d such that x < x0 < x + b d, and y < y0 < y + a d < y + B + b d. Therefore any enlargement of the box not containing a solution can contribute at mostB + b d· b d square units ofareaalongtherightsideoftheboxandsimilarlyalongtheleftside. Thus,thetotalcontribution is 4B + b d· b d square units of area. Therefore, the largest square area not containing a solution is at most