[tex]1)3k - 2k \\ = k(3 - 2) \\ = k(1) \\ = k[/tex]
[tex]2) {5x}^{2} - 10x - {8x}^{2} + x \\ = {5x}^{2} - {8x}^{2} - 10x + x \\ = - 3 {x}^{2} - 9x \\ = - 3x(x - 3)[/tex]
[tex]3) - (m + n) + 2(m - 3n) \\ = - m - n + 3m - 6n \\ = - m + 2m - n - 6n \\ = m - 7n [/tex]
Hope you could get an idea from here.
Doubt clarification - use comment section.
