Odpowiedź :
15 - a = 9
-a = 9 - 15
-a = -6
a = 6
-4x = -20 |:(-4)
x = 5
5x + 5 = 10 - 5x
5x + 5x = 10 - 5
10x = 5 |:10
x = 0,5
x + 6 + 3x = 10
x + 3x = 10 - 6
4x = 4 |:4
x = 1
9 + 4x - 1 = -5x + 1
4x + 5x = 1 + 1 - 9
9x = - 7 |:9
x = - [tex]\frac{7}{9}[/tex]
12 – 10x + 6 = 4x + 2 + 2x
-10x - 4x - 2x = 2 - 12 - 6
-16x = -16 |:(-16)
x = 1