Question

решите уравнения 5 кл (39+ х)-84=78

Answer 1

39+х=84+78
39+х=162
х=162-39
х=123

Answer 2

(39+х)-84=78
39+х=78+84
х=162-39
х=123

проверка
(39+123)-84=78
162-84=78
78=78