Giải thích các bước giải:
1) $\frac{-5}{2}$ : ( $\frac{3}{4}$ - $\frac{1}{2}$ )
= $\frac{-5}{2}$ : ( $\frac{3}{4}$ - $\frac{2}{4}$ )
= $\frac{-5}{2}$ : $\frac{1}{4}$
= $\frac{-5}{2}$ . 4
= -10
2) $\frac{298}{719}$($\frac{1}{4}$ + $\frac{1}{12}$ - $\frac{1}{3}$) - $\frac{2011}{2012}$
= $\frac{298}{719}$ : ( $\frac{3}{12}$ + $\frac{1}{12}$ - $\frac{4}{12}$ ) - $\frac{2011}{2012}$
= $\frac{298}{719}$ : 0 - $\frac{2011}{2012}$
= 0 - $\frac{2011}{2012}$
= $\frac{-2011}{2012}$
3) $\frac{27 . 18 + 27. 103 - 120 . 27}{15.33 + 33.12}$
= $\frac{27.( 18+103-120)}{33.( 15 + 12)}$
= $\frac{27.1}{33.27}$
= $\frac{1}{33}$