\[\boxed{\mathbf{1.}}\]
\[37 - 20 = 17\]
\[20 + 17 = 37\]
\[56 - 15 = 41\]
\[41 + 15 = 56\]
\[74 - 23 = 51\]
\[51 + 23 = 74\]
\[44 - 5 = 39\]
\[39 + 5 = 44\]
\[62 - 4 = 58\]
\[58 + 4 = 62\]
\[83 - 6 = 77\]
\[77 + 6 = 83\]
\[25 - 16 = 9\]
\[16 + 9 = 25\]
\[42 - 27 = 15\]
\[15 + 27 = 42\]
\[94 - 38 = 56\]
\[56 + 38 = 94\]