Решите пожалуйста 2.44

2.44.
1)
$(10a - 6b + 5c - 4d) - (9a - 2b - 4c + 2d) = 10a - 6b + 5c - 4d - 9a + 2b + 4c - 2d = a - 4b + 9c - 6d$
2)
$(5 {a}^{2} - ax + {x}^{2} ) + (3 {a}^{2} + 2ax - 3 {x}^{2} ) - (4ax + 2 {x}^{2} + {a}^{2} ) = 5 {a}^{2} - ax + {x}^{2} + 3 {a}^{2} + 2ax - 3 {x}^{2} - 4ax - 2 {x}^{2} - {a}^{2} = 7 {a}^{2} - 3ax - 4 {x}^{2}$
3)
$(2 {m}^{4} + 5 {m}^{3} n - 3 {m}^{2} {n}^{2} - m {n}^{3} ) + (3 {m}^{4} - 8 {m}^{3} {n}^{2} - 6m {n}^{3)} = 5 {m}^{4} + 5 {m}^{3} n - 3 {m}^{2} {n}^{2} - 7m {n}^{3} - 8 {m}^{3} {n}^{2}$