ГДЗ по алгебре 7 класс Макарычев Задание 72

\[\boxed{\text{72\ (72).}\text{\ }\text{Еуроки\ -\ ДЗ\ без\ мороки}}\]

\[\textbf{а)}\ 8,91\ + \ 25,7\ + \ 1,09\ = \ \]

\[= (8,91\ + \ 1,09) + \ 25,7\ = \ \]

\[= 10\ + \ 25,7\ = \ 35,7\]

\[\textbf{б)}\ 6,64\ + \ 7,12\ + \ 2,88\ =\]

\[= \ 6,64\ + \ (7,12\ + \ 2,88) = \ \]

\[= 6,64\ + \ 10\ = \ 16,64\]

\[\textbf{в)}\ 7,15\ - \ 9,42\ + \ 12,85\ - \ 0,58\ = \ \]

\[= (7,15\ + \ 12,85) - \ (9,42 + 0,58)\ = \ \]

\[= 20\ - \ 10\ = \ 10\]

\[\textbf{г)}\ 18,9\ - \ 6,8\ - \ 5,2\ - \ 4,1\ = \ \]

\[= (18,9\ - \ 4,1) - \ (6,8\ + \ 5,2)\ = \ \]

\[= 14,8\ - \ 12\ = \ 2,8\]