\(\left(19\frac{5}{8}:\frac{7}{12}-13\frac{1}{4}:\frac{7}{12}\right).\frac{4}{5}\)

\(=\left(\frac{157}{8}:\frac{7}{12}-\frac{53}{4}:\frac{7}{12}\right).\frac{4}{5}\)

\(=\left[\left(\frac{157}{8}-\frac{53}{4}\right):\frac{7}{12}\right].\frac{4}{5}\)

\(=\left[\frac{51}{8}:\frac{7}{12}\right].\frac{4}{5}\)

\(=\frac{153}{14}.\frac{4}{5}\)

\(=\frac{306}{35}\)

\(\left(\frac{-2}{5}+\frac{3}{7}\right)-\left(\frac{4}{9}+\frac{12}{20}-\frac{13}{35}\right)+\frac{7}{35}\)

\(=\frac{1}{35}-\frac{212}{315}+\frac{7}{35}\)

\(=\frac{1}{35}+\frac{-212}{315}+\frac{7}{35}\)

\(=\frac{9}{315}+\frac{-212}{315}+\frac{63}{315}\)

\(=\frac{-140}{315}=\frac{-4}{9}\)

\(\left(4\frac{5}{57}-3\frac{4}{51}+8\frac{13}{29}\right)-\left(3\frac{5}{57}-6\frac{16}{29}\right)\)

\(=\left(\frac{233}{57}-\frac{157}{51}+\frac{245}{29}\right)-\left(\frac{176}{57}-\frac{190}{29}\right)\)

\(=\frac{1941}{323}-\frac{-5726}{1653}\)

\(=\frac{14011}{1479}\)

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a) 2629x21-2526=52683 b) 42567+12312:24=43080 c) 115938:57-57=1977 d) 2/3+5/2-3/4=29/12 e)......tự làm

1: =-3x5+2x5-7x5+7x4=-8x5+7x4=-40+28=-12

2: =-3x5+3x6-4x3+4x2=-9+8=-1

3: =17(-84-16)=-1700

4: =1975(-115+15)=-197500

5: =-145x13+145x57+57x10-57x145=-1315

1/ \(5\left(-3+2\right)-7\left(5-4\right)\)

\(=5.\left(-3\right)+5.2-7.5-7.\left(-4\right)\)

\(=-15+10-35+28\)

\(=-5-7\)

\(=-12\)

2/ \(3.\left(-5+6\right)-4.\left(3-2\right)\)

\(=3.\left(-5\right)+3.6-4.3-4.\left(-2\right)\)

\(=-15+18-12+8\)

\(=3-4\)

\(=-1\)

3/ \(17.\left(-84\right)+17.\left(-16\right)\)

\(=17.\left(-84-16\right)\)

\(=17.\left(-100\right)\)

\(=-1700\)

4/ \(1975.\left(-115\right)+1975.15\)

\(=1975.\left(-115+15\right)\)

\(=1975.\left(-100\right)\)

\(=-197500\)

5/ \(-145.\left(13-57\right)+57.\left(10-145\right)\)

\(=-145.13-145.\left(-57\right)+57.10+57.\left(-145\right)\)

\(=-145.\left(-57+57\right)-145.13+57.10\)

\(=0-1885+570\)

\(=-1315\)

6/ \(157.17-157.7\)

\(=157.\left(17-7\right)\)

\(=157.10\)

\(=1570\)

7/ \(199.\left(15-17\right)-199.\left(-17+5\right)\)

\(=199.\left(-2\right)-199.\left(-12\right)\)

\(=199.\left(-2\right)+199.12\)

\(=199.\left(-2+12\right)\)

\(=199.10\)

\(=1990\)

8/ \(-39.\left(5-99\right)+99.\left(10-39\right)\)

\(=-39.5-39.\left(-99\right)+99.10+99.\left(-39\right)\)

\(=-39.\left(-99+99\right)-39.5+99.10\)

\(=0-195+990\)

\(=795\)

9/ \(-38.\left(25-4\right)+25.\left(-4+38\right)\)

\(=-38.25-38.\left(-4\right)+25.\left(-4\right)+25.38\)

\(=25.\left(-38+38\right)-4.\left(-38+25\right)\)

\(=0-4.\left(-13\right)\)

\(=52\)

10/ \(\left(-37\right).86+37.76\)

\(=37.\left(-86\right)+37.76\)

\(=37.\left(-86+76\right)\)

\(=37.\left(-10\right)\)

\(=-370\)

\(\dfrac{3}{5}+\dfrac{2}{3}=\dfrac{9}{15}+\dfrac{10}{15}=\dfrac{19}{15}\\ \dfrac{5}{7}-\dfrac{1}{2}=\dfrac{10}{14}-\dfrac{7}{14}=\dfrac{3}{14}\\ \dfrac{5}{6}\times\dfrac{4}{5}=\dfrac{1}{3}\times\dfrac{2}{1}=\dfrac{2}{3}\\ \dfrac{7}{9}:\dfrac{4}{3}=\dfrac{7}{9}\times\dfrac{3}{4}=\dfrac{7}{12}\)

\(\dfrac{3}{5}+\dfrac{2}{3}=\dfrac{9}{15}+\dfrac{10}{15}=\dfrac{19}{15}\)

\(\dfrac{5}{7}-\dfrac{1}{2}=\dfrac{10}{14}-\dfrac{7}{14}=\dfrac{3}{14}\)

\(\dfrac{5}{6}\text{×}\dfrac{4}{5}=\dfrac{5\text{×}4}{6\text{×}5}=\dfrac{2}{3}\)

\(\dfrac{7}{9}:\dfrac{4}{3}=\dfrac{7}{9}\text{×}\dfrac{3}{4}=\dfrac{7\text{×}3}{9\text{×}4}=\dfrac{7\text{×}3}{3\text{×}3\text{×}4}=\dfrac{7}{12}\)

\(\dfrac{3}{5}+\dfrac{2}{3}=\dfrac{9}{15}+\dfrac{10}{15} = \dfrac{19}{15}\)

\(\dfrac{5}{7}-\dfrac{1}{2}=\dfrac{10}{14}-\dfrac{7}{14}=\dfrac{3}{14}\)

\(\dfrac{5}{6} \times \dfrac{4}{5} = \dfrac{4}{6}= \dfrac{2}{3}\)

\( \dfrac{7}{9} : \dfrac{4}{3} = \dfrac{7}{9} \times \dfrac{3}{4} = \dfrac{7}{12}\)