
1. c) 5x + 3y = 0
3y = -5x
y = 
d) x - y = 5
y = 5 - x
2. 
3(
) - 7y = 17
y = 
x = 
x = 
3. 
2(-8y-6+4y) + 9 = 10y + 15
y = -1
x = -8(-1) - 6
x = 2
4. а) 8(x-2) = 6(2x+3)
8x - 16 = 12x + 18
8x - 12x = 18 + 16
-4x = 34
x =
= -8,5
б) 17 - 5y = -17y - 19
-5y + 17y = -19 - 17
12y = -36
y = -3
5. x - y = 12
2x + y = 27
3x = 39
x = 13
y = 27 - 2x = 27 - 2 * 13 = 27 - 26 = 1