Răspuns:
a)
2 • (7 + x : 3) = 21 - 1
2 • (7 + x : 3) = 20
7 + x : 3 = 10
x : 3 = 3
x = 9
b)
2 • (7 + 84 : x) = 98
7 + 84 : x = 49
84 : x = 42
x = 2
c)
[2 • (7 + x : 3) + 9] : 5 = 5
2 • (7 + x : 3) + 9 = 25
2 • (7 + x : 3) = 16
7 + x : 3 = 8
x : 3 = 1
x = 3
d)
(3000 - x) : 3 + 74 = 400
(3000 - x) : 3 = 326
3000 - x = 978
x = 3000 - 978
x = 2022
