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

= 27/17 + 24/17

= 3

cách 2 

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

=17/5 : 17/15

= 3

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 + 1,05 ) : 0,25

= 1,95 : 0,25

= 7,8

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

=27/17    +   24/17

=51/17=3

C1: \(\frac{9}{5}\div\frac{17}{15}+\frac{8}{5}\div\frac{17}{15}\)

 \(=\frac{27}{17}+\frac{24}{17}\)

\(=3\)

C2: \(\frac{9}{5}\div\frac{17}{15}+\frac{8}{5}\div\frac{17}{15}\)

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

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

\(=3\)

C1 :9/5 :17/15 +8/5 :17/`5                                                             C2 : ( 9/5 +8 /5 ) :17/15

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

=9*15 /5*17 + 8* 15 / 5 *17                                                             =3

27/17 + 24/17 =51/17 =3

mk trả lời đầu tiên đúng thì

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

0,9:0,25+1,05:0,25 = 0,9.4+1,05.4 = 4.(0,9+1,05)=4 . 1,95=7,8

 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

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

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

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

\(=4\cdot1,95\)

=\(7,8\)

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

=>17/5x15/17

=>17.15/17.5

=>15/5=3

ủng hộ mk nha tớ giải xong mà các bạn chưa giải cho cậu

C1: 9/5:17/15+8/5:17/15

= 27/17 + 24/17

=3

C2: 9/5:17/15+8/5:17/15

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

=17/1:17/15

=3

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

c1:=17/15:(9/5+8/5)

    =17/15:17/5=1

c2=27/17+24/17

    =51/17

C1 : \(\frac{9}{5}:\frac{17}{15}+\frac{8}{5}:\frac{17}{15}\)

\(=\frac{27}{17}+\frac{24}{17}\)

\(=3\)

C2 : \(\frac{9}{5}:\frac{17}{15}+\frac{8}{5}:\frac{17}{15}\)

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

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

\(=3\)

C1 :

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

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

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

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

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

C2 :

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

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

\(=\frac{27}{17}+\frac{24}{17}\)

\(=\frac{51}{17}=3\)

( 9/5 +  8/5 )  : 17 /15

= 17/15 : 17/15

=225/85=3

\(=\frac{\left(\frac{9}{5}+\frac{8}{5}\right)}{\frac{17}{15}}=\frac{\left(\frac{17}{5}\right)}{\left(\frac{17}{15}\right)}=\frac{255}{85}\)

\(=\frac{135}{85}+\frac{120}{85}=\frac{255}{85}\)