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nhóm các số có cùng mẫu với nhau rồi cộng ra

\(1)\frac{12}{7}\times \frac{7}{4}+\frac{35}{11}:\frac{245}{121}\)

\(=3+\frac{35}{11}\times \frac{121}{245}\)

\(=3+\frac{11}{7}\)

\(= 3\frac{1}{7}(=\frac{22}{7})\)

ms cs 1 câu nên mk chưa cho k đâu

5/9

26/45

1/14

19/24

3/5+4/6=3/5+2/3=9/15+10/15=19/15

7-1/3=20/3

5x3/8=15/8

12/35:2/5=12/35x5/2=60/70=6/7

\(\dfrac{3}{5}+\dfrac{4}{6}=\dfrac{3}{5}+\dfrac{2}{3}=\dfrac{19}{15}\)
\(7-\dfrac{1}{3}=\dfrac{20}{3}\)
\(5x\dfrac{3}{8}=\dfrac{15}{8}\)
\(\dfrac{12}{35}:\dfrac{2}{5}=\dfrac{12}{35}x\dfrac{5}{2}=\dfrac{6}{7}\)

\(y=12-\left(\dfrac{1}{3}\times4\right)=12-\dfrac{4}{3}=\dfrac{32}{3}\)

\(y=\left(\dfrac{12}{35}\times\dfrac{14}{9}\right)-\dfrac{2}{5}=\dfrac{8}{15}-\dfrac{2}{5}=\dfrac{2}{15}\)

a) \(y+\dfrac{1}{3}\times4=12\)

\(y+\dfrac{1}{3}=12:4\)

\(y+\dfrac{1}{3}=3\)

\(y=3-\dfrac{1}{3}\)

\(y=\dfrac{8}{3}\)

b) \(\dfrac{2}{5}+y=\dfrac{12}{35}\times\dfrac{14}{9}\)

    \(\dfrac{2}{5}+y=\dfrac{8}{15}\)

           \(y=\dfrac{8}{15}-\dfrac{2}{5}\)

          \(y=\dfrac{2}{15}\)

a)=12*7*5=60*7=420

b)25*24=5*5*6*4=30*20=600

a) 12 x 35 = 12 x 5 x 7 = 60 x 7 = 420

b) 25 x 24 = 25 x 4 x 6 = 100 x 6 = 600

\(\frac{18}{7}:9=\frac{18}{7}:\frac{9}{1}=\frac{18}{7}×\frac{1}{9}=\frac{9×2×1}{7×9}=\frac{2}{7}\)

\(\frac{64}{35}:4=\frac{64}{35}:\frac{4}{1}=\frac{64}{35}×\frac{1}{4}=\frac{16×4×1}{35×4}=\frac{16}{35}\)

\(\frac{24}{11}:12=\frac{24}{11}:\frac{12}{1}=\frac{24}{11}×\frac{1}{12}=\frac{12×2×1}{11×12}=\frac{2}{11}\)

\(\frac{35}{14}:5=\frac{35}{14}:\frac{5}{1}=\frac{35}{14}×\frac{1}{5}=\frac{5×7×1}{14×5}=\frac{7}{14}=\frac{1}{2}\)

18/17:9=18/17:9/1=18/17x1/9=2/17

64/35:4=64/35:4/1=64/35x1/4=16/35

24/11:12=24/11:12/1=24/11x1/12=2/11

35/4:5=35/4:5/1=35/4x1/5=7/4