Bài 5:

a) $\frac{15 x 35 x 12}{12 x 15 x 21}$ `=` $\frac{35}{21}$ 

b) $\frac{16 x 25 x 36}{10 x 16 x 36}$ `=` $\frac{25}{10}$ `=` $\frac{5}{2}$ 

c) $\frac{14 x 17 x 18}{17 x 28 x 24}$ `=` $\frac{14 x 17 x 18}{17 x 2 x 14 x 24}$ `=` $\frac{18}{2 x 24}$ `=` $\frac{2 x 9}{2 x24}$ `=` $\frac{9}{24}$

d) $\frac{14 x 17 x 23}{23 x 51 x 56}$ `=` $\frac{14 x17 x 23}{23 x 17 x 3 x 14 x 4}$ `=` $\frac{1}{3 x 4}$ `=` $\frac{1}{12}$ 

e) $\frac{11 x 12 x 18}{33 x 48 x 36}$ `=` $\frac{11 x 12 x 18}{11 x 3 x 12 x 4 x 18 x 2}$ `=` $\frac{1}{3 x 4 x 2}$ `=` $\frac{1}{24}$ 

g) $\frac{20 x 6 x 2}{10 x 16 x 24}$ `=` $\frac{2 x 10 x 6 x 2}{10 x 2 x8 x 4 x 6}$ `=` $\frac{2}{8x 4}$ `=` $\frac{2}{32}$ `=` $\frac{1}{16}$ 

Bài 6:

$\frac{3}{4}$ `=` $\frac{3 x 15}{4 x 15}$ `=` $\frac{45}{60}$ 

$\frac{8}{15}$ `=` $\frac{8 x 4}{15 x 4}$ `=` $\frac{32}{60}$ 

$\frac{19}{30}$ `=` $\frac{19 x 2}{30 x 2}$ `=` $\frac{38}{60}$ 

$\frac{2}{3}$ `=` $\frac{2 x 20}{3 x 20}$ `=` $\frac{40}{60}$ 

$\frac{4}{5}$ `=` $\frac{4 x 12}{5 x 12}$ `=` $\frac{48}{60}$ 

Bài 7:

a) $\frac{210}{168}$ `=` $\frac{210 : 2}{168 : 2}$ `=` $\frac{105}{84}$ 

b) $\frac{136}{368}$ `=` $\frac{136 : 8}{368 : 8}$ `=` $\frac{17}{46}$ 

HỌC TỐT!

~ 5 sao + hay nhất ạ ~ 

$CuCaixauxi$