Решите пожалуйста срочно то что выделено красным

Решите задачу:

$5x - 7xy + 4xy = \\ = 5x + ( - 7 + 4)xy = 5x - 3xy$
$4mn - {n}^{2} + {m}^{2} - 2mn = \\ = {m}^{2} - {n}^{2} + 2mn$
$2 {x}^{4} - 3x + 4 {x}^{2} - {x}^{4} + 4x = \\ = {x}^{4} + 4 {x}^{2} + x$
$- {x}^{4} + 3 {x}^{3} - 4 {x}^{4} - 2 {x}^{2} - 3 {x}^{2} = \\ = - 5 {x}^{4} + 3 {x}^{3} - 5 {x}^{2}$

$2 {m}^{4} - 3 {m}^{5} + {m}^{6} + \\ + 1 - {m}^{4} + 4 {m}^{5} - {m}^{6} = \\ = {m}^{5} + {m}^{4} + 1$
$- 5m + ( - m - n) = \\ = - 6m - n \\ 2x - 3y + ( - y - x) = \\ = x - 4y \\ 1.5 {a}^{2} + 2 {b}^{2} + 2 {a}^{2} - {b}^{2} = \\ = 3.5 {a}^{2} + {b}^{2}$