Đáp án:
`C=2`
Giải thích các bước giải:
$C=\dfrac{\dfrac{1}{3}-\dfrac{1}{5}-\dfrac{1}{13}}{\dfrac{2}{3}-\dfrac{2}{5}-\dfrac{2}{13}} : \dfrac{\dfrac{3}{5}-3+\dfrac{3}{25}}{1 \dfrac{3}{5}-8+\dfrac{8}{25}} + \dfrac{2}{3}$
$=\dfrac{\dfrac{1}{3}-\dfrac{1}{5}-\dfrac{1}{13}}{2.(\dfrac{1}{3}-\dfrac{1}{5}-\dfrac{1}{13})} : \dfrac{3.(\dfrac{1}{5}-1+\dfrac{1}{25})}{8.(\dfrac{1}{5}-1+\dfrac{1}{25})}+\dfrac{2}{3}$
$=\dfrac{1}{2} : \dfrac{3}{8} + \dfrac{2}{3} = \dfrac{4}{3} + \dfrac{2}{3} = 2$
