Пожалуйста помогите решить уравнения методом подстановки. 1) у=-3х 5х+3у=12 2) х-2у=5...

1) y = - 3x
5x + 3y = 12

y = -3
5x + 3*(-3x) = 12
5x - 9x = 12
-4x = 12
x = -3

x = -3
y = -3*3

x = -3
y = -9

2) x - 2y = 5
2x + 3y = -4

x = 5 + 2y
2(5 + 2y) + 3y = -4

10 + 4y + 3y = -4
7y = -4-10
7y = -14
y = -2

y = -2
x = 5 + 2*(-2)

y = -2
x = 1

3) 2x + 3y = 16
3x - 2y = 11

2x = 16 - 3y
3x - 2y = 11

x =(16 - 3y)/2
3* (16 - 3y)/2 - 2y = 11

(48 - 9y)/2 - 2y = 11
24 - 4,5y - 2y = 11
-6,5y = 11 - 24
- 6,5y = -13
y = -13 : (-6,5)
y = 2

x = (16 - 3*2)/2
x = 10/2
x = 5

x = 5
y = 2