\(\frac{9}{11}\)< \(\frac{13}{15}\)

\(\frac{19}{15}\)<    \(\frac{15}{11}\)

\(=\frac{15}{17}x\left(\frac{45}{13}-\frac{10}{13}-\frac{9}{13}-1\right)\\ =\frac{15}{17}x1=\frac{15}{17}\)

\(\frac{15}{17}\times\frac{45}{13}-\frac{15}{17}\times\frac{10}{13}-\frac{9}{13}\times\frac{15}{17}-\frac{15}{17}\)

\(=\frac{15}{17}\times\left(\frac{45}{13}-\frac{10}{13}-\frac{9}{13}-1\right)\)

\(=\frac{15}{17}\times1\)

\(=\frac{15}{17}\)

\(a.\) \(\frac{4}{15}.\frac{7}{9}+\frac{4}{15}.\frac{2}{9}\)

\(=\frac{4}{15}\left(\frac{7}{9}+\frac{2}{9}\right)\)

\(=\frac{4}{15}.\frac{9}{9}\)

\(=\frac{4}{15}.1\)

\(=\frac{4}{15}\)

\(b.\) \(\frac{13}{19}.\frac{23}{11}-\frac{13}{19}.\frac{8}{11}-\frac{13}{19}.\frac{4}{11}\)

\(=\frac{13}{19}\left(\frac{23}{11}-\frac{8}{11}-\frac{4}{11}\right)\)

\(=\frac{13}{19}.\frac{11}{11}\)

\(=\frac{13}{19}.1\)

\(=\frac{13}{19}\)

a)4/15 x(7/9+2/9)=4/15x1=4/15

b)13/19x(23/11-8/11-4/11)13/19x1=13/19

32/15x (15/4+ 15/8)

= 32/15x (30/8+ 15/8)

= 32/15x 45/8

= 12/1

=12

\(\frac{32}{15}\times\left(\frac{15}{4}+\frac{15}{8}\right)=\frac{32}{15}\times\left(\frac{30}{8}+\frac{15}{8}\right)\)

\(=\frac{32}{15}\times\frac{45}{8}=\frac{8\times4\times15\times3}{15\times8}=4\times3=12\)

Bằng \(\frac{200}{3}\)

kết quả bằng 200/3

Gọi số cần điền là a

Ta có \(\frac{13}{15}< \frac{17}{a}\le\frac{13}{14}\) 

=> \(\frac{13\times17}{15\times17}< \frac{13\times17}{13\times a}\le\frac{13\times17}{17\times14}\)

=> 15 x 17 > 13 x a \(\ge\)17 x 14

=> 255  > 13 x a \(\ge\)238

=> 13 x a = 247

=> a = 19

Vậy a = 19 

13/15 < 17/19 < 13/14

5-13/15

=75/15-13/15

=(75-13)/15

=62/15

5 - 13/15 = 5/1 - 13/15=75/15-13/15=62/15

=> x/4 = 15/12 - 13/20

=> x/4 = 3/5

=> x = 3/5 x 4 

=> x = 12/5

Tk mk nha