9+4*(х-2)=21
4(x-2) = 12
x - 2 = 3
x = 5
Проверка:
9 + 4(5 - 2) = 9 + 4 * 3 = 9 + 12 = 21
480:(34-х:7)=16
(34-х:7) = 480 : 16
34-х:7 = 30
x : 7 = 34 - 30
x : 7 = 4
x = 4 * 7
x = 28
480 : ( 34 - 28 : 7) = 480 : ( 34 - 4) = 480 : 30 = 16
9+4*(х-2)=21
4(x-2) = 12
x - 2 = 3
x = 5
Проверка:
9 + 4(5 - 2) = 9 + 4 * 3 = 9 + 12 = 21
480:(34-х:7)=16
(34-х:7) = 480 : 16
34-х:7 = 30
x : 7 = 34 - 30
x : 7 = 4
x = 4 * 7
x = 28
Проверка:
480 : ( 34 - 28 : 7) = 480 : ( 34 - 4) = 480 : 30 = 16