Для y = 4/5:
-2(3(4/5)-2,5) + 4,5(4/5) - 1 =-2(12/5 - 2,5) + 18/5 - 1 =-2(12/5 - 5/2) + 18/5 - 1 =-2((24/10) - (25/10)) + 18/5 - 1 =-2*(-1/10) + 18/5 - 1 =2/10 + 18/5 - 1 =1/5 + 18/5 - 1 =19/5 - 1 =(19 - 5)/5 =14/5.
Ответ: 14/5.
Для y = 4/5:
-2(3(4/5)-2,5) + 4,5(4/5) - 1 =
-2(12/5 - 2,5) + 18/5 - 1 =
-2(12/5 - 5/2) + 18/5 - 1 =
-2((24/10) - (25/10)) + 18/5 - 1 =
-2*(-1/10) + 18/5 - 1 =
2/10 + 18/5 - 1 =
1/5 + 18/5 - 1 =
19/5 - 1 =
(19 - 5)/5 =
14/5.
Ответ: 14/5.