BÀI TẬPBài 1: Tính:a) $\frac{3}{10}+(\frac{-5}{12})$b) $(\frac{-3}{8})-(-\frac{7}{24})$c)...

{
"answer1": {
"a": "a) $\frac{3}{10}+(\frac{-5}{12}) = \frac{3\times 6}{10\times 6} + \frac{-5\times 5}{12\times 5} = \frac{18}{60} - \frac{25}{60} = \frac{-7}{60}$",
"b": "b) $(\frac{-3}{8})-(-\frac{7}{24}) = \frac{-3\times 3}{8\times 3} - \frac{7\times 1}{24\times 1} = \frac{-9}{24} + \frac{7}{24} = \frac{-2}{24} = \frac{-1}{12}$",
"c": "c) $(\frac{-5}{14})+0.25 = \frac{-5}{14} + \frac{25}{100} = \frac{-5}{14} + \frac{25}{100} = \frac{-5}{14} + \frac{35}{140} = \frac{30}{140} = \frac{3}{14}$",
"d": "d) $(-\frac{7}{8})-1.25 = \frac{-7}{8} - \frac{125}{100} = \frac{-7}{8} - \frac{125}{100} = \frac{-7}{8} - \frac{100}{80} = \frac{-7}{8} - \frac{100}{80} = \frac{-70}{80} - \frac{100}{80} = \frac{-170}{80} = \frac{-17}{8}$"
},
"answer2": {
"e": "e) $(\frac{-5}{14})\times\frac{21}{25} = \frac{-5}{14} \times \frac{21}{25} = \frac{-5 \times 3}{14 \times 3} \times \frac{21}{25} = \frac{-15}{42} \times \frac{21}{25} = \frac{-105}{105} = -1$",
"f": "f) $\frac{8}{27}/(-\frac{16}{45}) = \frac{8}{27} \div \frac{-16}{45} = \frac{8}{27} \times \frac{-45}{16} = \frac{8\times(-45)}{27\times16} = \frac{-360}{432} = \frac{-5}{6}$",
"g": "g) $(1\frac{5}{6})/(4\frac{1}{8}) = \frac{11/6}{33/8} = \frac{11}{6} \times \frac{8}{33} = \frac{88}{198} = \frac{44}{99}$",
"h": "h) $0.38\times(\frac{-7}{19}) = \frac{38}{100} \times \frac{-7}{19} = \frac{38 \times -7}{100 \times 19} = \frac{-266}{1900} = \frac{-133}{950}$"
},
"answer3": {
"i": "i) $(\frac{-4}{5})\times(\frac{15}{-8})\times1\frac{1}{9} = \frac{-4}{5} \times \frac{15}{-8} \times \frac{19}{9} = \frac{-4 \times 15 \times 19}{5 \times -8 \times 9} = \frac{-1140}{-360} = 3$"
},
"answer4": {
"a": "a) $\frac{3}{10}+(\frac{-5}{12}) = \frac{3}{10} - \frac{5}{12} = \frac{18}{60} - \frac{25}{60} = -\frac{7}{60}$",
"b": "b) $(\frac{-3}{8})-(-\frac{7}{24}) = \frac{-3}{8} + \frac{7}{24} = \frac{-9}{24} + \frac{7}{24} = -\frac{2}{24} = -\frac{1}{12}$",
"c": "c) $(\frac{-5}{14})+0.25 = \frac{-5}{14} + \frac{25}{100} = \frac{-5}{14} + \frac{35}{140} = \frac{30}{140} = \frac{3}{14}$",
"d": "d) $(-\frac{7}{8})-1.25 = \frac{-7}{8} - \frac{125}{100} = \frac{-7}{8} - \frac{100}{80} = \frac{-70}{80} - \frac{100}{80} = \frac{-170}{80} = -\frac{17}{8}$"
}
}