The four planes 7x + 4y – 4z + 2 = 0,  36x–51y + 12z + 17 = 0, 14x+8y–8z–12= 0 and 12x–17y+4z–1=0  are the four faces of a

. 14x + 3y – 8 z + 4 = 0

14x + 8y – 8 z – 12 = 0

$d_1=\frac{4+12}{\sqrt{{14}^2+8^2+8^2}}$

36x -  51y + 12z+12 = 0

36x – 51y +12z – 3 = 0

$d_2=\frac{17+3}{\sqrt{{\left(36\right)}^2+{\left(51\right)}^2+{12}^2}}$

$d_1\ne d_2$

The adjacent planes are perpendicular so that the planes are forms rectangular parallalopipe