Giải giúp em với ạ =)))

Giải thích các bước giải:

Ta có:

$A=3\dfrac1{117}\cdot\dfrac1{119}-\dfrac4{117}\cdot 5\dfrac1{119}-\dfrac5{117\cdot 119}+\dfrac8{39}$

$\to A=(3+\dfrac1{117})\cdot\dfrac1{119}-\dfrac4{117}\cdot (5+\dfrac1{119})-\dfrac5{117\cdot 119}+\dfrac8{39}$

$\to A=\dfrac3{119}+\dfrac1{117\cdot 119}-\dfrac{20}{117}-\dfrac4{117\cdot 119}-\dfrac5{117\cdot 119}+\dfrac8{39}$

$\to A=\dfrac3{119}-\dfrac{20}{117}+\dfrac8{39}+\dfrac1{117\cdot 119}-\dfrac4{117\cdot 119}-\dfrac5{117\cdot 119}$

$\to A=\dfrac3{119}-\dfrac{20}{117}+\dfrac8{39}-\dfrac8{117\cdot 119}$

$\to A=\dfrac3{119}-\dfrac{20}{117}+\dfrac8{117}\cdot (3-\dfrac1{119}) $

$\to A=\dfrac3{119}-\dfrac{20}{117}+\dfrac8{117}\cdot \dfrac{356}{119}$

$\to A=\dfrac3{119}-\dfrac{20}{117}+\dfrac8{117}\cdot \dfrac{356}{119}$

$\to A=\dfrac{351}{13923}-\dfrac{2380}{13923}+\dfrac{2848}{13923}$

$\to A=\dfrac{819}{13923}$

$\to A=\dfrac1{17}$