4) 2a-((2b-3c)-d)+a-(2b-(c-d))+a+(2b-(c+2d)) = 2a - (2b - 3c - d) + a - (2b - c + d) + a + (2b - c - 2d) = 2a - 2b + 3c + d + a - 2b + c - d + a + 2b - c - 2d = 4a - 2b + 3c - 2d
Ответ: 4a - 2b + 3c - 2d