Объяснение:

1. y = 2x - 3

6x + 2 (2x - 3) = 4

10x - 6 = 4

10x = 10

x = 1

y = 1 * 2 - 3

y = -1

2. a) y = 2x - 5, x = 2,5 + 0,5y

б) u = -7 - 8,5v

v = -14/17 - 2/17u

3. 11x - 150 = 30 - 7x

11x + 7x = 150 + 30

18x = 180

x = 10

y = 30 - 7 * 10

y = -40

4. x - первое, y - второе,

x - y = 7

x = 7 + y

y/100 = x/135

135y = 100x

135y = 700 + 100y

35y = 700

y = 20, x = 27

1.  x = 11 - y

a) 2 ( 11 - y) - y = -5

22 - 3y = -5

3y = 27

y = 9, x = 2

б) y = 5 - 2x

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

7x - 10 = 4

7x = 14

x = 2, y = 1

2. x - первое, y - второе,

x + y = 22

x - y= 8

x = y + 8

2y + 8 = 22

2y = 14

y = 7

x = 15