4) 5 - |x - $\frac{2}{3}$| - 2 = x
⇔ |x - $\frac{2}{3}$| = x - 5 + 2
⇔ |x - $\frac{2}{3}$| = x - 3
TH1: x - $\frac{2}{3}$ = x - 3
⇔ x - x = -3 + $\frac{2}{3}$
⇔ 0 = $\frac{-7}{3}$ (vô lí)
TH2: x - $\frac{2}{3}$ = -(x - 3)
⇔ x - $\frac{2}{3}$ = -x + 3
⇔ x + x = 3 + $\frac{2}{3}$
⇔ 2x = $\frac{11}{3}$
⇔ x = $\frac{11}{6}$
Vậy x = $\frac{11}{6}$