Cách làm cho bạn:
a. $(\frac{9}{25}-2.18)\div (3\frac{4}{5}+0,2)$;
= $(0,36-36)\div (3,8+0,2)$
= $-35,64\div 4$
= $-8,91$
b. $\frac{5}{18}-1,456\div \frac{7}{25}+4,5.\frac{4}{5}$
= $\frac{5}{18}-1,456\div 0,28+4,5.0,8$
= $\frac{5}{18}-5,2+3,6$
= $\frac{5}{18}-(5,2-3,6)$
= $\frac{5}{18}-1,6$
= $\frac{5}{18}-\frac{8}{5}$
= $\frac{25}{90}-\frac{144}{90}$
= $\frac{-119}{90}$
= $-1\frac{29}{90}$
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