
Подставим значение y во второе уравнение
-2x + 3(2x - 1) = 9
-2x + 6x - 3 = 9
4x - 3 = 9
4x = 12
x = 3
y = 2 * 3 - 1
y = 5
(x, y) = (3, 5)
б) 
Подставим значение x в первое уравнение
3(-5y - 4) - 7y = 32
-15y - 12 - 7y = 32
-22y - 12 = 32
-22y = 44
y = -2
x = -5 * (-2) - 4
x = 6
(x, y) = (6, -2)
в)

Подставим значение 4x во второе уравнение
-(40 - 7y) + 9y = 24
-40 + 7y + 9y = 24
-40 + 16y = 24
16y = 24 + 40
16y = 64
y = 4
-4x + 9 * 4 = 24
-4x = 24 - 36
-4x = -12
x = 3
(x, y) = (3, 4)
г)

Подставим значение y в первое уравнение
2x - 3(7 - 5x) = -4
2x - 21 + 15x = -4
17x - 21 = -4
17x = 17
x = 1
y = 7 - 5 * 1
y = 2
(x, y) = (1, 2)
д) 

Подставим значение x в первое уравнение



39 + 46y = -99
39 + 46y = -99
46y = -99 - 39
46y = -138
y = -3

x = -2
(x, y) = (-2, -3)