a: =35/17-18/17-9/5+4/5

=1-1=0

b: =-7/19(3/17+8/11-1)

=7/19*18/187=126/3553

c: =26/15-11/15-17/3-6/13

=1-6/13-17/3

=7/13-17/3=-200/39

= 26/7 x 11/3 - 26/7 x 8/3

= 26/7 x (11/3 - 8/3)

= 26/7 x 1

= 26/7

( 11/3 - 8/3) x 26/7 = 3/3 x 26/7 = 1 x 26/7= 26/7

\(=\dfrac{26}{17}\cdot\left(\dfrac{11}{3}-\dfrac{8}{3}\right)=\dfrac{26}{17}\cdot1=\dfrac{26}{17}\)

\(\frac{2}{3}\)x \(\frac{5}{8}\)x \(\frac{8}{15}\)= \(\frac{2}{3}\)x \(\frac{1}{15}\)= \(\frac{2}{45}\)

\(\frac{22}{5}\)x \(12\)x \(\frac{20}{40}\)= \(\frac{22}{5}\)x \(12\)x \(\frac{1}{2}\)= \(\frac{22}{5}\)x 6 = \(\frac{122}{5}\)

\(\frac{7}{2}\)x \(\frac{26}{7}\)x \(\frac{4}{13}\)= \(\frac{91}{7}\)x \(\frac{4}{13}\)

a) 21/11.22/17.68/63

=21/11.11.2/17.17.4/3.21

=21.11.2.17.4/11.17.3.21

=8/3

b) 5/14.7/13.26/25

=5/2.7.7/13.2.13/5.5

=5.7.2.13/2.7.13.5.5

=1/5

6 phần 13 nhân 8 phần 7 nhân âm 26 phần 3 nhân âm 7 phần 8 = 4

\(\frac{7}{19}.\frac{8}{11}+\frac{7}{19}.\frac{3}{11}-\frac{26}{19}\)

\(=\frac{7}{19}.\left(\frac{8}{11}+\frac{3}{11}\right)-\frac{26}{19}\)

\(=\frac{7}{19}.1-\frac{26}{19}\)

\(=\frac{7}{19}-\frac{26}{19}\)

\(=\frac{-19}{19}=-1\)

1: \(\dfrac{-7}{4}\cdot\dfrac{2}{9}=\dfrac{-14}{36}=\dfrac{-7}{18}\)

2: \(=\dfrac{12}{13}\cdot\dfrac{26}{5}=\dfrac{24}{5}\)

3: \(=\dfrac{20}{11}\cdot\dfrac{55}{21}=\dfrac{100}{21}\)

4: \(=\dfrac{-40}{240}=\dfrac{-1}{6}\)