$\\$
$\dfrac{(3 \dfrac{1}{4}-x) . 4 \dfrac{1}{25} - 12,13}{ (x-1 \dfrac{3}{7}) : 1 \dfrac{1}{49}+\dfrac{2}{5} }=2$
`-> (3 1/4 - x) . 4 1/25 - 12,13 = [(x - 1 3/7) : 1 1/49 + 2/5] . 2`
`-> (13/4 -x) .101/25 - 1213/100 = [(x - 10/7) : 50/49 + 2/5] . 2`
`-> 13/4 . 101/25 - 101/25x - 1213/100 = [(x-10/7) . 49/50 +2/5] . 2`
`-> 1313/100 - 101/25x - 1213/100 = [49/50x - 49/50 . 10/7 + 2/5] . 2`
`-> (1313/100 - 1213/100) - 101/25x = [49/50x - 7/5 + 2/5] . 2`
`-> 1-101/25x = [49/50x + (-7/5 +2/5)].2`
`-> 1 - 101/25x = [49/50x - 1] . 2`
`-> 1 - 101/25x = 49/25x - 2`
`-> (-101)/25x - 49/25x = -1 - 2`
`-> ( (-101)/25 - 49/25)x = -3`
`-> -6x = -3`
`->x=-3 : (-6)`
`->x=1/2`
Vậy `x=1/2`
