3abc - 5a²b + [ abc - (4ab² - 3a²b)]
= 3abc - 5a²b + abc - 4ab² + 3a²b
= 4abc - 2a²b - 4ab²
= 2ab(2c - a - 2b)
= 2×(-2)×(-1)×[2×1/4 - (-2) - 2×(-1)]
= 4×(1/2 +2 +2)
= 4× 9/2
= 18