\[\boxed{\mathbf{14.}}\]
\[\textbf{а)}\ 60 - (10 + 20) = 60 - 30 =\]
\[= 30\]
\[50 + (40 - 30) = 50 + 10 = 60\]
\[\textbf{б)}\ 30 + (70 - 10) = 30 + 60 =\]
\[= 90\]
\[80 - (30 + 30) = 80 - 60 = 20\]
\[80 - (35 - 5) = 80 - 30 = 50\]
\[60 + (58 - 50) = 60 + 8 = 68\]