\[\boxed{\mathbf{2}\mathbf{.}\mathbf{152}}\]
\[\textbf{а)}\ PM = 373\ мм;\ \ MN = z\ мм;\ \ \]
\[NQ = 75\ мм:\]
\[PQ = 373 + z + 75 =\]
\[= z + (373 + 75) = z + 448.\]
\[z = 225:\]
\[225 + 448 = 673\ мм.\]
\[z = 384:\]
\[384 + 448 = 832\ мм.\]
\[\textbf{б)}\ PQ = 226\ мм;\ \ MN = 74\ мм;\ \ \]
\[NQ = z\ мм:\]
\[PM = PQ - MN - NQ =\]
\[= 226 - 74 - z =\]
\[= (226 - 74) - z = 152 - z.\]
\[z = 47:\]
\[152 - 47 = 105\ мм.\]
\[z = 105:\]
\[152 - 105 = 47\ мм.\]