$\dfrac{3}{4}$ `+` $\dfrac{5}{8}$ `: x = ` $\dfrac{1}{12}$
`<=>` $\dfrac{5}{8}$ `: x = ` $\dfrac{1}{12}$ `-` $\dfrac{3}{4}$
`<=>` $\dfrac{5}{8}$ `: x =` $-\dfrac{2}{3}$
`<=>` $x =$ $-\dfrac{5}{8}$ `:` $(-\dfrac{2}{3})$
`<=>` `x = ` $-\dfrac{15}{16}$ `
Vậy `x=` $-\dfrac{15}{16}$ `
`- huonggiang20102007 -`