A. 9/15 : 7/5 + 8/5 : 17/5                                         B. 100% + 28,4% - 36,7%

 = ( 9/15 + 8/5 ) : 7/5                                                = 128,4% - 36,7%

 =   33/15 : 7/5                                                          = 91,7%

 =  11/7

C. 25 : 5/11 = 55                                                    D. 8/7 : 4 = 2/7

~ Chúc bạn học tốt ~

a,-5/9 + 8/18 + -2/11 + 4/-9 + 7/15                                            b,5/17 + -9/15 + -2/17 + 2/5 + 14/17

= -5/9 + 4/9 + -2/+ 4/-9 + 7/15                                                 = 5/17 + -3/5 + -2/17 + 2/5 + 14/17

=(-5/9 + 4/9 + -4/9 ) +-2/11 + 7/15                                            = ( 5/17 + -2/17 + 14/17) + ( 2/5 + -3/5)

= -1/3 + -2/11 + 7/15                                                               =1 + -1/5

=-75/225 + -30/ 225 + 77/225                                                  =4/5              

= -25/225 = -1/9                                                                        ( 4/5 = 0.8 )

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

 A) cách 1\(\frac{9}{5}:\frac{17}{15}+\frac{8}{5}:\frac{17}{15}\)

\(=\frac{9}{5}\cdot\frac{15}{17}+\frac{8}{5}\cdot\frac{15}{17}\)

\(=\frac{135}{85}+\frac{120}{85}\)

\(=\frac{255}{85}\)

\(=3\)

Cách 2\(\frac{9}{5}:\frac{17}{15}+\frac{8}{5}:\frac{17}{15}\)

\(=\frac{9}{5}\cdot\frac{15}{17}+\frac{8}{5}\cdot\frac{15}{17}\)

\(=\frac{15}{17}\cdot\left(\frac{9}{5}+\frac{8}{5}\right)\)

=\(\frac{15}{17}\cdot\frac{17}{5}\)

\(=\frac{15\cdot17}{17\cdot5}\)

\(=\frac{5\cdot3\cdot17}{17\cdot5}\)

\(=3\)

B) Cách 1 :

0,9 : 0,25 + 1,05 : 0,25

= 3,6 + 4,2

=7,8

Cách  2:

0,9 : 0,25 + 1,05 : 0,25

\(=0,9:\frac{1}{4}+1,05:\frac{1}{4}\)

\(=0,9\cdot4+1,05\cdot4\)

\(=4\cdot\left(0,9+1,05\right)\)

\(=4\cdot1,95\)

=\(7,8\)

= 17/15 : ( 9/5 + 8,5 )

=  17/15 :17/5

= 1/3

\(\dfrac{9}{5}:\dfrac{17}{15}+\dfrac{8}{5}:\dfrac{17}{15}=\dfrac{9}{5}\times\dfrac{15}{17}+\dfrac{8}{5}\times\dfrac{15}{17}=\dfrac{15}{17}\times\left(\dfrac{9}{5}+\dfrac{8}{5}\right)=\dfrac{15}{17}\times\dfrac{17}{5}=\dfrac{255}{85}=3\)

9/5 : 17/15 + 8/5 : 17/15= 17/15 : ( 9/5 + 8,5 )

                                      =  17/15 :    17/5

                                      =      1/3

= 51/17

sao lai ra 51/17 vay ban

      \(\frac{9}{5}:\frac{17}{15}+\frac{8}{5}:\frac{17}{15}\)

\(=\frac{17}{15}:\left(\frac{9+8}{5}\right)\)

\(=\frac{17}{15}:\frac{17}{5}\)

\(=\frac{17}{15}X\frac{5}{17}\)

\(=\frac{1}{3}\)

Chúc bn học tốt

Tk cho mình nhé

\(\frac{9}{5}:\frac{17}{15}+\frac{8}{5}:\frac{17}{15}=\frac{9}{5}.\frac{15}{17}+\frac{8}{5}.\frac{15}{17}=\frac{15}{17}\left(\frac{9}{5}+\frac{8}{5}\right)=\frac{15}{17}.\frac{17}{5}=3\)

\(\frac{9}{5}:\frac{17}{15}+\frac{8}{5}:\frac{17}{15}\)= \(\left(\frac{9}{5}+\frac{8}{5}\right):\frac{17}{15}\)

=\(\frac{17}{5}.\frac{15}{17}\)= 3

9/5 : 17/15 + 8/5 : 17/15

= 17/15 : ( 9/5 + 8/5 )

= 17/15 : 17/5

= 1/3

9/5:17/15+8/5:17/15

=(9/5+8/5):17/15

=17/5:17/15

=3

Chúc bạn học giỏi nha!!!

K cho mik vs nhé Tuyên

9/5:17/15+8/5+17/15

=(9/5+8/5):17/15

=17/5:17/15

=3

la 3 day