1. В) I-54,997I = 54,997
2. -(9у-7х+23z) = -9y+7x-23z
3. 1,2х-3 = -27
1,2х = -27+3
1,2х = -24
х = -24:1,2
х = -20
4. 13 - (6,6 - 2 8/15) * 3 = 0,8
1) 6,6 - 2 8/15 = 6 6/10 - 2 8/15 = 6 3/5 - 2 8/15 = 6 9/15 - 2 8/15 = 4 1/15
2) 4 1/15 * 3 = 12 3/15 = 12 1/5
3) 13 - 12 1/5 = 12 5/5 - 12 1/5 = 4/5 = 0,8