60 − 8 * 5 = 20
49 : 7 − 7 = 0
(81 − 9) : 9 + 18 : 9 = 10
(54 : 6 − 9) * 7 + 162 = 162

Вычисления:
60 − 8 * 5 = 60 − 40 = 20
$\begin{array}{r}\begin{array}{r}-\end{array}\underline{\begin{array}{r}60\\ 40\end{array}}\\ \begin{array}{r}20\end{array}\end{array}$
49 : 7 − 7 = 7 − 7 = 0
(81 − 9) : 9 + 18 : 9 = 72 : 9 + 18 : 9 = 8 + 2 = 10
$\begin{array}{r}\begin{array}{r}-\end{array}\underline{\begin{array}{r}81\\ 9\end{array}}\\ \begin{array}{r}72\end{array}\end{array}$
(54 : 6 − 9) * 7 + 162 = (9 − 9) * 7 + 162 = 0 * 7 + 162 = 0 + 162 = 162