x² - 5x + 6 = 0,
Д = 25 - 24 = 1,
х1 = (5 + 1) / 2 = 6/2 = 3,
х2 = (5 - 4) / 2 = 4/2 = 2
х:8/9=3/4
х=8/9*3/4
х=2/3
12/х=33/7/4
х= 12/33/7/4
х=12*7/33*1/4
х=7/11