$\frac{18}{27}$ + $\frac{4}{19}$ + $\frac{1}{3}$
= $\frac{342}{513}$ + $\frac{108}{513}$ + $\frac{171}{513}$
= $\frac{23}{19}$
a, x - $\frac{2}{65}$ = $\frac{4}{39}$
x = $\frac{4}{39}$ + $\frac{2}{65}$
x = $\frac{2}{15}$.
Vậy x = $\frac{2}{15}$.
b,$\frac{1}{115}$ - x = $\frac{-4}{25}$
x = $\frac{1}{115}$ - $\frac{-4}{25}$
x = $\frac{97}{575}$.
Vậy x = $\frac{97}{575}$.
