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