Ответ:

(х-20.9)+12.27=23.2

х - 20,9 = 23, 2 - 12,27

х - 20, 9 = 10,93

х = 10,93 + 20,9

х = 31, 83

(х-20.9)+12.27=23.2

х-20.9=23.2-12.27

х-20.9=10.93

х=10.93+20.9

х=31.83