6.
[tex]-4(6a+5b) = -4\cdot6a -4\cdot5b = \boxed{-24a - 20b}\\\\\underline{Odp. \ B}[/tex]
7.
[tex]\frac{(6^{2})^{6}\cdot6}{6^{12}} = \frac{6^{2\cdot6}\cdot6}{6^{12}} = \frac{6^{12}\cdot6}{6^{12}} = \boxed{6}\\\\\underline{Odp. \ A.}[/tex]
8.
[tex]\sqrt{1\frac{9}{16}} = \sqrt{\frac{1\cdot16+19}{16}}=\sqrt{\frac{25}{16}} = \frac{\sqrt{25}}{\sqrt16}}= \frac{\sqrt{5^{2}}}{\sqrt{4^{2}}} =\boxed{ \frac{5}{4}}\\\\\underline{Odp. \ D.}[/tex]
9.
[tex]\sqrt{20} = \sqrt{4\cdot5}=\sqrt{4}\cdot\sqrt{5} =\boxed{2\sqrt{5}}\\\\\underline{Odp. \ D.}[/tex]
10.
a)
[tex]3x+4 = 16 \ \ \ |-4\\\\3x = 12 \ \ \ /:3\\\\\boxed{x = 4}[/tex]
b)
[tex]6x-5 = x+4\\\\6x-x = 4+5\\\\5x = 9 \ \ \ /:5\\\\\boxed{x = \frac{9}{5} = 1\frac{4}{5}}[/tex]
