= (5/6 + 7/6) + (4/15 + 11/15)
= 2 + 1

= 3 

=(5/6+7/6)+(4/15+11/15)

=12/6+15/15

=2+1

=3

\(=\left(\dfrac{5}{6}+\dfrac{7}{6}\right)+\left(\dfrac{4}{15}+\dfrac{11}{15}\right)=\dfrac{12}{6}+1=2+1=3\)

=(5/6+7/6)+(4/15+11/15)

=12/6+15/15

=2+1

=3

14/15 + 6/11 + 1/15 + 5/11 + 22/11

=(14/15 +1/15)+(6/11 + 5/11 + 22/11)

=1+3

=4

\(\frac{11}{15}\cdot\frac{6}{7}+\frac{11}{15}\cdot\frac{8}{7}\) 

\(=\frac{11}{15}\cdot\left(\frac{6}{7}+\frac{8}{7}\right)\) 

\(=\frac{11}{15}\cdot2=\frac{22}{15}\)

Chú ý dấu "  \(\cdot\) " là dấu nhân

      11/15 x 6/7 + 11/15 x 8/7 

=    11/15 x (6/7 + 8/7)

=     11/15 x 2

=      22/15.

Mik ko chắc lắm nhé !

a.\(\dfrac{18}{15}+\dfrac{7}{15}+\dfrac{12}{15}=\dfrac{18+7+12}{15}=\dfrac{37}{15}\)

b.\(\dfrac{9}{7}+\dfrac{8}{7}+\dfrac{11}{7}=\dfrac{9+8+11}{7}=\dfrac{28}{7}=4\)

chưa kịp xem hết ý a =')

(2/7+5/7)+4/9=1+4/9=13/9

17/11+(7/15+5/11)=17/11+7/15+5/11=(17/11+5/11)+7/15=2+5/11=27/11

Ta có: \(\frac94\times\frac{15}{11}+\frac34:\frac{11}{7}-\frac34\times\frac{8}{11}\)

\(=\frac34\times\frac{45}{11}+\frac34\times\frac{7}{11}-\frac34\times\frac{8}{11}\)

\(=\frac34\times\left(\frac{45}{11}+\frac{7}{11}-\frac{8}{11}\right)=\frac34\times\frac{44}{11}=3\)