\[\boxed{\text{43\ (43).}\text{\ }\text{Еуроки\ -\ ДЗ\ без\ мороки}}\]
Пояснение.
Решение.
\[1)\ 760 - (120 + 80) + 60 =\]
\[= 760 - 200 + 60 = 560 + 60 =\]
\[= 620.\]
\[2)\ 500 - (270 + 130) - 1 =\]
\[= 500 - 400 - 1 = 100 - 1 =\]
\[= 99.\]
\[3)\ 120\ :(60\ :6)\ :2 =\]
\[= 120\ :10\ :2 = 12\ :2 = 6.\]
\[4)\ 90\ :(45\ :9) \cdot 2 =\]
\[= 90\ :5 \cdot 2 = 18 \cdot 2 = 36.\]