a)\(\dfrac{-10}{11}.\dfrac{8}{9}+\dfrac{7}{18}.\dfrac{10}{11}\)

=\(\dfrac{10}{11}.\dfrac{-8}{9}+\dfrac{7}{18}.\dfrac{10}{11}\)

=\(\dfrac{10}{11}(\dfrac{-8}{9}+\dfrac{7}{18})\)

=\(\dfrac{10}{11}.\dfrac{-1}{2}\)

=\(\dfrac{-5}{11}\)

b; 

B = \(\dfrac{3}{14}\) : \(\dfrac{1}{28}\) - \(\dfrac{13}{21}\): \(\dfrac{1}{28}\) + \(\dfrac{29}{42}\) : \(\dfrac{1}{28}\) - 8

B = (\(\dfrac{3}{14}\) - \(\dfrac{13}{21}\) + \(\dfrac{29}{42}\)) - 8

B = (\(\dfrac{9}{42}\) - \(\dfrac{26}{42}\) + \(\dfrac{29}{42}\)) - 8

B = (\(\dfrac{-17}{42}\) + \(\dfrac{29}{42}\)) - 8

B = \(\dfrac{2}{7}\) - 8

B = \(\dfrac{2}{7}-\dfrac{56}{7}\)

B = - \(\dfrac{54}{7}\)

c; C = -1\(\dfrac{5}{7}\).15 + \(\dfrac{2}{7}\)(-15) + (-105).(\(\dfrac{2}{3}\) - \(\dfrac{4}{5}\) + \(\dfrac{1}{7}\))

C = - 15.(- 1 - \(\dfrac{5}{7}\) + \(\dfrac{2}{7}\) + \(\dfrac{14}{3}\) - \(\dfrac{28}{5}\) + \(1\))

C = -15.[(1 - 1) - (\(\dfrac{5}{7}\) - \(\dfrac{2}{7}\)) + \(\dfrac{14}{3}\) - \(\dfrac{28}{5}\)]

C = -15.[0 - \(\dfrac{3}{7}\) + \(\dfrac{14}{3}\) - \(\dfrac{28}{5}\)]

C = -15 . [- \(\dfrac{45}{105}\) + \(\dfrac{490}{105}\)  - \(\dfrac{588}{105}\)]

C = -15. [ \(\dfrac{445}{105}\) - \(\dfrac{588}{105}\)]

C = - 15.(- \(\dfrac{143}{105}\))

C = \(\dfrac{143}{7}\)

a) 2/9 - (1/20 + 2/9)

= 2/9 - 1/20 - 2/9

= (2/9 - 2/9) - 1/20

= 0 - 1/20

= -1/20

b) -3/14 + 2/13 + (-25/14) + (-15/13)

= (-3/14 - 25/14) + (2/13 - 15/13)

= -2 - 1

= -3

c) -3/11 + 11/8 - 3/8 + (-8/11)

= (-3/11 - 8/11) + (11/8 - 3/8)

= -1 + 1

= 0

d) 3/8 + (-1/4) - (7/12 - 1/6)

= 1/8 - 5/12

= -7/24

e) (1/3 + 12/67 + 13/41) - (79/67 - 28/41)

= 1/3 + 12/67 + 13/41 - 79/67 + 28/41

= 1/3 + (12/67 - 79/67) + (13/41 + 28/41)

= 1/3 - 1 + 1

= 1/3

a)\(x+\frac{15}{16}+\frac{7}{8}=\frac{15}{4}\)

\(x+\frac{29}{16}=\frac{15}{4}\)

\(x=\frac{15}{4}-\frac{29}{16}\)

\(x=\frac{31}{16}\)

b)\(x-\frac{27}{28}-\frac{9}{14}=\frac{13}{7}\)

\(x-\frac{45}{28}=\frac{13}{7}\)

\(x=\frac{13}{7}+\frac{45}{28}\)

\(x=\frac{97}{28}\)

c)\(x\times\frac{1}{5}+x+\frac{1}{6}=\frac{2}{3}\)

\(x\times\frac{1}{5}+x=\frac{2}{3}-\frac{1}{6}\)

\(x\times\left(\frac{1}{5}+1\right)=\frac{1}{2}\)

\(x\times\frac{6}{5}=\frac{1}{2}\)

\(x=\frac{1}{2}:\frac{6}{5}\)

\(x=\frac{5}{12}\)

d)\(x:14=\frac{1}{4}+\frac{2}{9}+\frac{3}{4}\)

\(x:14=\frac{11}{9}\)

\(x=\frac{11}{9}\times14\)

\(x=\frac{154}{9}\)

#H

\(\frac{7}{8}>\frac{7}{9}>\frac{7}{10}>\frac{7}{11}>\frac{7}{15}\)
Tính :
\(a,\frac{1}{4}+\frac{3}{8}+\frac{5}{16}=\frac{4+6+5}{16}=\frac{15}{16}\)
\(b,\frac{3}{5}-\frac{1}{3}-\frac{1}{6}=\frac{18-10-5}{30}=\frac{3}{30}=\frac{1}{10}\)
\(c,\frac{4}{7}\times\frac{5}{8}\times\frac{7}{12}=\frac{5}{14}\times\frac{7}{12}=\frac{5}{24}\)
\(d,\frac{25}{28}:\frac{15}{14}\times\frac{6}{7}=\frac{25\times14\times6}{28\times15\times7}=\frac{5}{7}\)

\(\frac{7}{15}< \frac{7}{11}< \frac{7}{10}< \frac{7}{9}< \frac{7}{8}\)

\(a=\frac{15}{16};b=\frac{1}{10}\)

\(c=\frac{5}{24};d=\frac{5}{7}\)

7/8; 7/9; 7/10; 7/11; 7/15

a: 15/16

b:1/10

c:5/24

d:5/7

_Tao quên cách làm rồi chi ạ ( Bi = Jin :)) )