6.72 : (203.2 - х) = 2.1

1.3 х+3.8 х-0.03=2.01

I) 1.3 х + 3.8 х-0.03=2.01

1.3 х + 3.8 х = 2.01 + 0.03

5.1 х = 2.04

х = 2.04/5.1

х = 0.4

Проверка:

5.1 * 0.4 = 2.04

2.04 = 2.04

Ответ: х=0.4

II) 6.72 / (203.2 - х) = 2.1

203.2 - x = 6.72/2.1

203.2 - х = 3.2

х = 203.2 - 3.2

х = 200

Проверка:

6.72 / (203.2 - 200) = 2.1

6.72/3.2 = 2.1

2.1 = 2.1

Ответ: х=200