[tex]4a + 8 = 10 \\ 4a = 10 - 8 \\ 4a = 2 \\ a = 0.5[/tex]

[tex]1) \: \: \: \: \: {a}^{2} + 4ab + 4b = ( {0.5)}^{2} + 4 \times 0.5b + 4b = 0.25 + 2b + 4b = 0.25 + 6b[/tex]

[tex]2) \: \: \: \: \: 2b + a = 2b + 0.5[/tex]

[tex]3) \: \: \: \: \: 2a + 4b = 2 \times 0.5 + 4b = 1 + 4b[/tex]