2/7 + 3/5

= 10/35 + 21/35  

= 31/35

   31/35 - 2/7  

= 31/35 - 10/35  

= 21/35

= 3/5

   31/35 - 2/5

= 31/35 - 14/35  

= 17/35

   3/5 + 2/7  

= 21/35 + 10/35

= 31/35

2/7 + 3/5 = 10/35 + 21/35 = 31/35

31/35 - 2/7 = 31/35 - 10/35 = 21/35

31/35 - 2/5 = 31/35 - 21/35 = 10/35

3/5 + 2/7 = 21/35 + 10/35 = 31/35

2/7+3/5 =31/35

31/35-2/7=21/35

31/35-2/5=17/35

3/5+2/7=31/35

nhớ tích cho minh nhé mình kb cho mình là con gái

a) \(6-\dfrac{2}{5}+\dfrac{3}{5}\) x \(3\)

\(=6-\dfrac{2}{5}+\dfrac{9}{5}\)

\(=\dfrac{30}{5}-\dfrac{2}{5}+\dfrac{9}{5}\)

\(=\dfrac{30-2+9}{5}=\dfrac{37}{5}\)

b) \(\left(\dfrac{31}{35}-\dfrac{4}{7}\right)\) x \(\dfrac{8}{7}:2\)

\(=\left(\dfrac{31}{35}-\dfrac{20}{35}\right)\) x \(\dfrac{8}{7}:2\)

\(=\dfrac{11}{35}\) x \(\dfrac{8}{7}:2\)

\(=\dfrac{11}{35}\) x \(\dfrac{8}{7}\) x \(\dfrac{1}{2}\)

\(=\dfrac{\text{11 x 8 x 1}}{\text{ 35 x 7 x 2}}=\dfrac{88}{490}=\dfrac{88}{245}\)  

a) 6−25+356−25+35 x 33

=6−25+95=6−25+95

=305−25+95=305−25+95

=30−2+95=375=30−2+95=375

b) (3135−47)(3135−47) x 87:287:2

=(3135−2035)=(3135−2035) x 87:287:2

=1135=1135 x 8

\(\frac{6-2}{5}+\frac{3}{5.3}\)

\(=\frac{4}{5}+\frac{1}{5.1}\)

\(=\frac{4}{5}+\frac{1}{5}\)

\(=\frac{5}{5}=1\)

a. 6 x 3 - ( \(\frac{2}{5}+\frac{3}{5}\)) = 6 x 3 - \(\frac{5}{5}\)= 6 x 3 - 1 = 18 - 1 = 17

b.(  \(\frac{31}{35}-\frac{4}{7}\)) x \(\frac{8}{7}\): 2 =\(\frac{11}{35}\)x \(\frac{8}{7}\): 2 =\(\frac{88}{245}\): 2 = \(\frac{88}{490}\)= \(\frac{44}{245}\)= ...........rút gọn đến khi hết

a) \(6-\frac{2}{5}+\frac{3}{5}\times3\)

\(=6-\frac{2}{5}+\frac{9}{5}\)

\(=\frac{30}{5}-\frac{2}{5}+\frac{9}{5}\)

\(=\frac{28}{5}+\frac{9}{5}\)

\(=\frac{37}{5}\)

b) \(\left(\frac{31}{35}-\frac{4}{7}\right)\times\frac{8}{7}:2\)

\(=\frac{11}{35}\times\frac{8}{7}:2\)

\(=\frac{88}{245}:2\)

\(=\frac{44}{245}\)

bạn lên mạng tra từng câu 1 sẽ có

ukm cảm ơn bạn nhìu

Bài 1: 

Ta có: \(x-35\%\cdot x=\dfrac{1}{25}\)

\(\Leftrightarrow65\%\cdot x=\dfrac{1}{25}\)

\(\Leftrightarrow x=\dfrac{1}{25}:\dfrac{13}{20}=\dfrac{1}{25}\cdot\dfrac{20}{13}=\dfrac{4}{65}\)

Vậy: \(x=\dfrac{4}{65}\)

Bài 2: 

a) Ta có: \(17\dfrac{2}{31}-\left(\dfrac{15}{17}+6\dfrac{2}{31}\right)\)

\(=17\dfrac{2}{31}-\dfrac{15}{17}-6\dfrac{2}{31}\)

\(=11+\dfrac{2}{31}-\dfrac{15}{17}\)

\(=\dfrac{5366}{527}\)

`31/35-2/7`

`=31/35-10/35`

`=21/35=3/5`

BT1 :thực hành phép tính

4/3+-11/31+3/10-20/31-2/5 = 7/30

7/12-1/-16+3/4 = 67/48

2/11.-5/4+-9/11.5/4+ 1 và 3/4 = -1/4 * và 3/4 là sao bạn *

-9/27-25/75 = -2/3

\(6-\frac{2}{5}+\frac{3}{5}\times3\)

\(=\frac{30}{5}-\frac{2}{5}+\frac{9}{5}\)

\(=\frac{30-2+9}{5}\)

\(=\frac{37}{5}\)

\(\left(\frac{31}{35}-\frac{4}{7}\right)\times\frac{8}{7}\div2\)

\(=\left(\frac{31}{35}-\frac{20}{35}\right)\times\frac{8}{14}\)

\(=\frac{11}{35}\times\frac{4}{7}\)

\(=\frac{44}{245}\)