Условие:

Найди значения выражений, используя сочетательное свойство сложения.
(48 + 27) + 3
(254 + 86) + 14
(57 + 692) + 8
(399+ 299) + 1

(48 + 27) + 3 = 48 + (27 + 3) = 78
(254 + 86) + 14 = 254 + (86 + 14) = 354
(57 + 692) + 8 = 57 + (692 + 8) = 757
(399+ 299) + 1 = 399 + (299 + 1) = 699
Вычисления:
(48 + 27) + 3 = 48 + (27 + 3) = 78
$\begin{array}{r}\begin{array}{r}+\end{array}\underline{\begin{array}{r}27\\ 3\end{array}}\\ \begin{array}{r}30\end{array}\end{array}$
$\begin{array}{r}\begin{array}{r}+\end{array}\underline{\begin{array}{r}48\\ 30\end{array}}\\ \begin{array}{r}78\end{array}\end{array}$
(254 + 86) + 14 = 254 + (86 + 14) = 354
$\begin{array}{r}\begin{array}{r}+\end{array}\underline{\begin{array}{r}86\\ 14\end{array}}\\ \begin{array}{r}100\end{array}\end{array}$
$\begin{array}{r}\begin{array}{r}+\end{array}\underline{\begin{array}{r}254\\ 100\end{array}}\\ \begin{array}{r}354\end{array}\end{array}$
(57 + 692) + 8 = 57 + (692 + 8) = 757
$\begin{array}{r}\begin{array}{r}+\end{array}\underline{\begin{array}{r}692\\ 8\end{array}}\\ \begin{array}{r}700\end{array}\end{array}$
$\begin{array}{r}\begin{array}{r}+\end{array}\underline{\begin{array}{r}57\\ 700\end{array}}\\ \begin{array}{r}757\end{array}\end{array}$
(399+ 299) + 1 = 399 + (299 + 1) = 699
$\begin{array}{r}\begin{array}{r}+\end{array}\underline{\begin{array}{r}299\\ 1\end{array}}\\ \begin{array}{r}300\end{array}\end{array}$
$\begin{array}{r}\begin{array}{r}+\end{array}\underline{\begin{array}{r}399\\ 300\end{array}}\\ \begin{array}{r}699\end{array}\end{array}$