$215 = xD_1 + R$

$167 = xD_1 + R$

$135 = xD_3 + R$

We have to maximize $x$

$$x = \frac{48}{D_1 – D_2} = \frac{80}{D_1 – D_3} = \frac{32}{D_2 – D_3}$$

$$x = \frac{16\times 3}{D_1 – D_2} = \frac{16\times5}{D_1 – D_3} = \frac{16\times2}{D_2 – D_3}$$

Now if the system $$D_1 – D_2 = 3\\D_1 – D_3 = 5\\D_2 – D_3 = 2$$ is solvable then $x = 16$ would be our answer.

Now rank of the matrix

$$Rank({\begin{bmatrix}1 & -1 & 0\\ 1 & 0 & -1\\ 0 & 1 & -1\end{bmatrix}}) = 2$$

So it has infinite solutions, so $x = 16$ is our answer.