\[\boxed{\mathbf{6}\mathbf{.}}\]
\[\textbf{а)}\ 27 + 5 = 32\]
\[39 + 4 = 43\]
\[58 + 3 = 61\]
\[15 + 8 = 23\]
\[26 + 6 = 32\]
\[44 + 7 = 51\]
\[\textbf{б)}\ 14 + 9 + 30 = 23 + 30 = 53\]
\[29 + 8 + 12 = 29 + 20 = 49\]
\[35 + 6 - 20 = 41 - 20 = 21\]
\[58 - 2 + 9 = 56 + 9 = 65\]
\[77 - 30 + 7 = 47 + 7 = 54\]
\[83 + 9 + 8 = 92 + 8 = 100\]