а) 2.3 * 0.6 - x = 2.3
1.38 - x = 2.3
-x = 2.3 - 1.38
-x = 0.92
x = -0.92

б) -у + 1 2/3 = -2 1/6
-у + 5/3 = -13/6
-у = -13/6 - 5/3
-у = -13/6 - 10/6
-у = -23/6
y = 23/6