Урок 2(47) Сочетательное свойство сложения. Скобки. Вычислительные умения и навыки.
= 16 = = = = = = = 98
(21 + 9) (9 + 7) (38 + 7) (7 + 3) (56 + 9) (9 + 1) ( ) (27 + 3) = 37 = 48 = 66 = 99
= = = = = = = = = ( )