`{3x - 2}/4 = {5y+3}/2 = {3x+5y +1}/{3x} = {3x -2 - 3x - 5y -1}{3x} = {5y+3 - 3x - 5y - 1}/{3x}`
`=> 3x -2 - 3x - 5y -1 = 5y+3 - 3x - 5y -1`
`=> -3 - 5y = 2 -3x `
`=> 5y +3x = -3 -2 = -5`
Khi đó :
`{3x - 2}/4 = {5y+3}/2 = {3x - 2 +5y +3}/{4+2} = {-5 -2 +3}/{4+2} = {-2}/3`
$\begin{cases} 3x - 2 = \dfrac{-8}{3} \\ \dfrac{5y+3}/2 = \dfrac{-4}{3} \end{cases}$
$\begin{cases} x = \dfrac{-2}{9} \\ y = \dfrac{-13}{15} \end{cases}$
Khi đó :
`{3x+5y+1}/{3x} = {7}/{3 . {-2}/9} = 7 . {-3}/2 = {-21}/2`
