a) x + $\frac{1}{3}$ x = $\frac{1}{2}$
⇔ ( x + 1 ) . 2 = 3x . 1
⇔ x . 2 + 1 . 2 = 1x . 3
⇔ x . 2 + 3 = 1x . 3
⇔ x . 2 - 1 = -3 . 3
⇔ x = -6
Vậy x = -6
b) 2x + $\frac{1}{5}$ = x + $\frac{2}{3}$
⇔ ( 2x + 1 ) . 3 = 5 . ( x + 2 )
⇔ ( 3x ) . 3 = 5 . ( x + 2 )
⇔ 3 . 3 . 3x = 5 . x + 5 . 2
⇔ 27x = 5x + 10
⇔ 27x - 5x = 12
⇔ 22x = 12
⇔ x = 12 : 22
⇔ x = $\frac{12}{22}$
Vậy x = $\frac{12}{22}$
