Đáp án:
`a)`
` -1,8 + (1+ \frac{4}{5}) = -1,8 + ( 1 + 0,8)`
` = -1,8 + 1,8`
` = 0`
`b)`
`\frac{11}{21} + \frac{5}{6} : \frac{6}{8} - \frac{5}{6}. \frac{6}{7}`
` = \frac{11}{21} + \frac{10}{9} - \frac{5}{7}`
` = \frac{103}{63} - \frac{5}{7}`
` = \frac{58}{63}`
`c)`
`\frac{-3}{8}.16.\frac{8}{17} - 0,375. \frac{79}{17}`
` = \frac{-3}{18}. \frac{128}{17} + \frac{-3}{8}. \frac{79}{17}`
` = \frac{-3}{18}. (\frac{128}{17} + \frac{-273}{136})`
` = \frac{-3}{18}. \frac{787}{136}`
` =\frac{-787}{816}`
`d)`
` \frac{-1}{2}: 1\frac{3}{8} - 25%. (-6\frac{2}{11})`
` = \frac{-1}{2} : \frac{11}{8} - \frac{1}{4}. \frac{-68}{11}`
` = \frac{-11}{16} - \frac{-17}{11}`
` = \frac{17}{16}`
