3,2(x-4y)+(5y-x) при x=0,4 и y=2/3

3,2 * (x - 4 * y)+(5 * y - x) при x = 0,4 и y = 2/3; 
3,2 * ( 0,4 - 4 * 2/3) + (5 * 2/3 - 0,4) = 4 8/25. 
1). 4 * 2/3 = 4*2 / 3 = 8/3;
2). 0,4 - 8/3 = 4/10 - 8/3 = 4*3/10*3 - 8 *10/3*10 = 12/30 - 80/30 = - 68/30 = - 34/15;
3). 3,2 * (-34/15) = 32/10 * (- 34/15) = - 32 * 34 / 10 * 15 = - 1088/150;
4). 5 * 2/3 = 5*2 / 3 = 10/3;
5). 10/3 - 0,4 = 10/3 - 4/10 = 10/3 - 2/5 = 10*5/10*5 - 2*3/5*3 = 50/15 - 6/15 = 44/15;
6). - 1088/150 + 44/15 = - 1088/150 + 440/150 = - 648/150 = - 216/50 = - 108/25 = 4 8/25.
Ответ: 4 8/25.