`(-2)/3 . [ (7,2 - 2/5) . x - 3/13] = 1 1/15`
`(-2)/3. [ (36/5 - 2/5) . x - 3/13] = 1 1/15`
`(-2)/3 . [34/5 . x - 3/13] = 16/15`
`34/5 . x - 3/13 = 16/15 : (-2)/3`
`34/5 . x - 3/13 = 16/15 xx (-3)/2`
`34/5 . x - 3/13 = (-8)/5`
`34/5 . x = (-8)/5 + 3/13`
`34/5 . x = (-89)/65`
`x=(-89)/65 : 34/5`
`x = (-89)/65 xx 5/34`
`x=(-89)/442`
Vậy `x=(-89)/442`
`-2/3 * [(7,2 - 2/5) * x -3/13] = 1 1/15`
`<=> -2/3 * [(36/5 - 2/5 )*x - 3/13 ] = 16/15`
`<=> [(36/5 - 2/5 )*x - 3/13 ] = 16/15 : (-2/3)`
`<=>34/5 *x - 3/13 = -8/5`
`<=> 34/5* x = -8/5 + 3/13`
`<=> 34/5* x = =-89/65`
`<=> x = -89/65 : 34/5 = -89/442`