Odpowiedź:
2. a) 120% - 84
100% - x
120x = 8400
x = [tex]\frac{8400}{120}[/tex] = [tex]\frac{840}{12}[/tex] = 70
b) 1,2x = 0,5x + 7
1,2x - 0,5x = 7
0,7x = 7
x = 10
c) 2x + 10 = 16
2x = 6
x = 3
d) 4x - 20 = x + 1
4x - x = 1 + 20
3x = 21
x = 7
3. a) -2(4 - 5x) = 20
-8 + 10x = 20
10x = 28
x = 2,8
b) -2 - (4 - 3x) = 9 + 2x
-2 - 4 + 3x = 9 + 2x
3x - 2x = 9 + 4 + 2
x = 15
c) 4 - 3x = 5(2 - x)
4 - 3x = 10 - 5x
-3x + 5x = 10 - 4
2x = 6
x = 3
