84. Решите уравнение: 1) 17n - 11n - 2n = 511; 2) 23a - 8a - 13a = 33; 3) 4x + 6x - x = 21,6; 4) 7y - y + 3y = 61,2.

1) 17n - 11n - 2n = 511
(17 - 11 - 2)n = 511
4n = 511
n = 511 / 4
n = 127.75
2) 23a - 8a - 13a = 33
(23 - 8 - 13)a = 33
2a = 33
a = 33 / 2
a = 16.5
3) 4x + 6x - x = 21,6
(4 + 6 - 1)x = 21.6
9x = 21.6
x = 21.6 / 9
x = 2.4
4) 7y - y + 3y = 61,2
(7 - 1 + 3)y = 61.2
9y = 61.2
y = 61.2 / 9
y = 6.8