$80 \overset{5}{-} (49 \overset{1}{+} 14) \overset{2}{:} 9 \overset{3}{*} 8 \overset{6}{-} 6 \overset{4}{*} 4 = 80 - 63 : 9 * 8 - 24 = 80 - 7 * 8 - 24 = 80 - 56 - 24 = 24 - 24 = 0$
1) 49 + 14 = 63;
2) 63 : 9 = 7;
3) 7 * 8 = 56;
4) 6 * 4 = 24;
5) 80 − 56 = 24;
6) 24 − 24 = 0.

$7 \overset{4}{*} (24 \overset{2}{-} 3 \overset{1}{*} 6) \overset{7}{+} 64 \overset{5}{:} (32 \overset{3}{:} 4) \overset{6}{*} 6 = 7 * (24 - 18) + 64 : 8 * 6 = 7 * 6 + 8 * 6 = 42 + 48 = 90$
1) 3 * 6 = 18;
2) 24 − 18 = 6;
3) 32 : 4 = 8;
4) 7 * 6 = 42;
5) 64 : 8 = 8;
6) 8 * 6 = 48;
7) 42 + 48 = 90.

$81 \overset{6}{:} (27 \overset{1}{:} 3) \overset{7}{-} 0 * (7 \overset{2}{*} 7) \overset{8}{+} (36 \overset{3}{:} 4 \overset{5}{+} 5 \overset{4}{*} 8) = 81 : 9 - 0 * 49 + (9 + 40) = 9 - 0 + 49 = 58$
1) 27 : 3 = 9;
2) 7 * 7 = 49;
3) 36 : 4 = 9;
4) 5 * 8 = 40;
5) 9 + 40 = 49;
6) 81 : 9 = 9;
7) 9 − 0 = 9;
8) 9 + 49 = 58.