$48 \overset{2}{:} 8 \overset{5}{+} 7 \overset{4}{*} (72 \overset{1}{:} 8) \overset{6}{-} 6 \overset{3}{*} 8 = 21$
1) 72 : 8 = 9;
2) 48 : 8 = 6;
3) 7 * 9 = 63;
4) 6 * 8 = 48;
5) 6 + 63 = 69;
6) 69 − 48 = 21.
 
$8 \overset{3}{*} 7 \overset{6}{+} (2 \overset{1}{*} 9) \overset{4}{:} 3 \overset{7}{-} 81 \overset{5}{:} (16 \overset{2}{-} 7) = 53$
1) 2 * 9 = 18;
2) 16 − 7 = 9;
3) 8 * 7 = 56;
4) 18 : 3 = 6;
5) 81 : 9 = 9;
6) 56 + 6 = 62;
7) 62 − 9 = 53.