a)
[tex]\frac{8}{-z} = \frac{5}{3}, \ \ \ \ \ Zal: \ z\neq 0\\\\-5z = 24 \ \ \ |:(-5)\\\\\boxed{z = -4\frac{4}{5}}[/tex]
b)
[tex]\frac{3}{5} = \frac{2y-5}{4}\\\\5(2y-5) = 12\\\\10y - 25 = 12\\\\10y = 12+25\\\\10y = 37 \ \ \ |:10\\\\\boxed{y = 3\frac{7}{10}}[/tex]
c)
[tex]\frac{2}{y-3} = \frac{3}{y-2}, \ \ \ \ \ Zal: \ y\neq 3 \ \ i \ \ y\neq 2\\\\3(y-3) = 2(y-2)\\\\3y-9 = 2y-4\\\\3y-2y = -4+9\\\\\boxed{y = 5}[/tex]
