a)
[tex]3a + 6 - 4a - 3 + 5a - 4 = 4a - 1 \\ \\ 4 \times ( - 4) - 1 = - 16 - 1 = - 17[/tex]
b)
[tex]4x + 2y + 10 - 5x + 8y = - x + 10y + 10[/tex]
[tex] - 2 + 10 \times ( - 0.7) + 10 = - 2 + ( - 7) + 10 = - 2 - 7 + 10 = - 9 + 10 = 1[/tex]
