А)
2y - (4 - y) = -6 (2y + 3) + 4
2y - 4 + y = -12y - 18 + 4
3y + 12y = -18 + 4 + 4
15y = -10
3y = -2
y = -2/3
y = минус две третьих
б) 1 1/3 (3/4 t - 1/4) + 0.7t = 3/8
4/3 (3/4 t - 1/4) + 0.7t = 3/8
t - 1/3 + 0.7t = 3/8
1.7t = 3/8 + 1/3
1.7t = 9/24 + 8/24
1.7t = 17/24
17/10 t = 17/24
t = 17/24 : 17/10
t = 17/24 * 10/17
t = 10/24 = 5/12
t = пять двенадцатых