\[\boxed{\mathbf{2}\mathbf{.}}\]
\[19 + 5 = 19 + 1 + 4 = 20 + 4 =\]
\[=\]
\(24\)=
\[28 + 4 = 28 + 2 + 2 = 30 + 2 =\]
\[= 32\]
\[37 + 6 = 37 + 3 + 3 = 40 + 3 =\]
\[= 43\]
\[49 + 7 = 49 + 1 + 6 = 50 + 6 =\]
\[= 56\]
\[55 + 9 = 55 + 5 + 4 = 60 + 4 =\]
\[= 64\]
\[76 + 8 = 76 + 4 + 4 = 80 + 4 =\]
\[= 84\]