zad. 1
c = [tex]\frac{a + x}{b}[/tex] | *b
cb = a + x | -a
x = cb - a
zad. 2
y = z - [tex]\frac{x+1}{2}[/tex] | *2
2y = z - x + 1 | -1
2y -1 = z - x | -z
-x = 2y - 1 - z
x = -2y + 1 + z
