Giúp mình với ạ mai mình thi rồi ạ

$\sqrt{\frac{25}{81}}$ : $\frac{10}{9}$ + $(\frac{-2}{3})^{2}$ : 0,9 + ($\frac{1}{2021})^0$

= $\frac{5}{9}$ : $\frac{10}{9}$ + $\frac{4}{9}$ : $\frac{9}{10}$ + 1

= $\frac{1}{2}$ + $\frac{40}{81 }$ + 1

= $\frac{161}{162}$ + 1

= $\frac{323}{162}$

$\frac{5x-2}{3}$ = $\frac{-3}{4}$ 

⇒ (5x-2) . 4 = 3 . (-3)

⇒ (5x-2) . 4 = -9 

       5x-2     = -9 : 4 

       5x - 2   = $\frac{-9}{4}$ 

        5x       = $\frac{-9}{4}$  + 2

         5x      = $\frac{-1}{4}$ 

           x      = $\frac{-1}{4}$  : 5 

           x      = $\frac{-1}{20}$ 

($x^{2}$ -$\frac{1}{4}$ ) ( x + $\frac{2}{5}$ = 0 => $\left \{ {{x^{2} -\frac{1}{4} = 0} \atop {x + \frac{2}{5} = 0 }} \right.$ => $\left \{ {{x^{2} = \frac{1}{4} } \atop {x =\frac{-2}{5} }} \right.$ => $\left \{ {{x = ±\frac{1}{2}} \atop {x\frac{-2}{5}}} \right.$