Đáp án:
1. Tính
a) `\frac{21}{25}` : `\frac{3}{5}` = `\frac{21}{25}` . `\frac{5}{3}` = `\frac{7}{5}`
b) `\frac{-12}{30}` : `(``-18``)` = `\frac{-12}{30}` : `\frac{-18}{1}` = `\frac{-12}{30}` . `\frac{1}{-18}` = `\frac{1}{45}`
c) `(``-100``)` : `\frac{-5}{3}` = `\frac{-100}{1}` : `\frac{-5}{3}` = `\frac{-100}{1}` . `\frac{3}{-5}` = `60`