a) \(\dfrac{3}{5}-\dfrac{3}{5}.\dfrac{2}{3}=\dfrac{3}{5}-\left(\dfrac{3}{5}.\dfrac{2}{3}\right)=\dfrac{3}{5}-\dfrac{2}{5}=\dfrac{1}{5}\) 

b) \(\dfrac{-7}{9}.\dfrac{11}{15}-\dfrac{4}{15}.\dfrac{-7}{9}-\dfrac{7}{9}=\dfrac{-7}{9}.\left(\dfrac{11}{15}-\dfrac{4}{15}\right)-\dfrac{7}{9}=\dfrac{-7}{9}.\dfrac{7}{15}-\dfrac{7}{9}=-\dfrac{49}{135}-\dfrac{7}{9}=-\dfrac{154}{135}\)

d) \(3\dfrac{1}{7}-\left(4\dfrac{1}{2}+5\dfrac{3}{7}\right)=\dfrac{22}{7}-\left(\dfrac{9}{2}+\dfrac{38}{7}\right)=\dfrac{22}{7}-\left(\dfrac{63}{14}+\dfrac{76}{14}\right)=\dfrac{22}{7}-\dfrac{139}{14}=\dfrac{44}{14}-\dfrac{139}{14}=-\dfrac{95}{14}\)

a) 2 50 - 3 98 + 4 32 - 5 72

= 10 2 - 21 2  + 16 2  - 30 2

= -25 2

1) 5 + (-4) = 1

2) (-8) + 2 = -6

3) 8 + (-2) = 6

4) 11 + (-3) = 8

5) (-11) + 2 = -9

6) (-7) + 3 = -4

7) (-5) + 5 = 0

8) 11 + (-12) = -1

9) (-18) + 20 = 2

10) (15) + (-12) = 3

11) (-17) + 17 = 0

12) 16 + (-2) = 14

13) (30) + (-14) = 16

14) (-19) + 20 = 1

15) (-18) + 15 = -3

16) (10) + (-6) = 4

17) (-28) + 14 = -14

18) 15 + (-30) = -15

19) (15) + (-4) = 11

20) (-21) + 11 = -10

21) 8 + (-22) = -14

22) (-15) + 4 = -11

23) (-3) + 2 = -1

24) 17 + (-14) = 3

25) 17 + (-14) = 3

thế này đọc đc mới đỉnh

tách ra bn

khó nhìn quá:V

Chóng mặttttttttttttttt!

Còn câu c nữa quên : 9 phần 7 nhân (3 phần 7 trừ 1 phần 2 )

kí hiệu /:phần,kí hiệu'."nhân

a)5/4-5/8+-2/3=30/24+15/24+(-16/24)=29/24

b)7/19.8/11+7/19.3/11+12/19

=7/19.(8/11+3/11)+12/19

=7/19.11/11+12/19

=7/19.1+12/19

=7/19+2/19=9/19

chúc học tốt!

c) 9/7.(3/7-1/2) =9/7.(6/14-7/14)=9/7.(-1/14)=-9/98

cho mik xin bài giải với ạ

Sao toàn viết chữ thế ? Đọc sao nổi ? Viết lại ra số đi

\(a.\frac{2}{3}+\frac{1}{5}\cdot\frac{10}{7}\)

\(=\frac{2}{3}+\frac{1\cdot2}{1\cdot7}\)

\(=\frac{2}{3}+\frac{2}{7}=\frac{2\cdot7}{21}+\frac{2\cdot3}{21}=\frac{14}{21}+\frac{6}{21}=\frac{20}{21}\)

\(b.\frac{2}{7}\cdot\frac{4}{7}+\frac{2}{7}\cdot\frac{3}{7}\)

\(=\frac{2}{7}\cdot\left(\frac{4}{7}+\frac{3}{7}\right)\)

\(=\frac{2}{7}\cdot\frac{7}{7}=\frac{2}{7}\cdot1=\frac{2}{7}\)

\(c.\left[-\frac{1}{4}+\frac{3}{10}\right]:\left(-\frac{3}{5}\right)-\frac{7}{6}\)

\(=\left[-\frac{5}{20}+\frac{6}{20}\right]:\left(-\frac{3}{5}\right)-\frac{7}{6}\)

\(=\frac{1}{20}:\left(-\frac{3}{5}\right)-\frac{7}{6}\)

\(=\frac{1}{20}\cdot\left(-\frac{5}{3}\right)-\frac{7}{6}\)

\(=\frac{1\cdot\left(-1\right)}{4\cdot3}-\frac{7}{6}\)

\(=\left(-\frac{1}{12}\right)-\frac{7}{6}=\left(-\frac{1}{12}\right)-\frac{14}{12}=-\frac{15}{12}\)

bài 2 :a) \(2x-2\frac{2}{7}=2\frac{5}{7}\)

\(2x=2\frac{5}{7}-2\frac{2}{7}\)

\(2x=\left(2-2\right)+\left(\frac{5}{7}-\frac{2}{7}\right)\)

\(2x=0+\frac{3}{7}\)

\(2x=\frac{3}{7}\)

\(x=\frac{3}{7}:2=\frac{3}{7}\cdot\frac{1}{2}=\frac{3}{14}\)

\(b.\frac{17}{13x}=\frac{4}{39}\)

\(\Rightarrow13x\cdot4=17\cdot39\)

\(\Rightarrow13x\cdot4=663\)

\(\Rightarrow13x=663:4\)

\(\Rightarrow13x=165,75\)

\(\Rightarrow x=165,75:13\)

\(\Rightarrow x=12,75\)

\(****nha!!!!!!!!!!!!\)

dung may inh la tinh ra 

\(\frac{7}{8}\div\left(\frac{14}{3}+\frac{14}{4}\right)+\frac{10}{14}\)

\(=\frac{7}{8}\div\left(\frac{56}{12}+\frac{52}{12}\right)+\frac{10}{14}\)

\(=\frac{7}{8}\div\frac{108}{12}+\frac{10}{14}\)

\(=\frac{7}{8}\div9+\frac{5}{7}\)

\(=\frac{7}{8}\times\frac{1}{9}+\frac{5}{7}\)

\(=\frac{7}{72}+\frac{5}{7}\)

\(=\frac{49}{504}+\frac{360}{504}\)

\(=\frac{409}{504}\)

\(\frac{30}{42}\div\left(\frac{5}{7}-\frac{5}{21}\right)+\frac{6}{8}\)

\(=\frac{6}{7}\div\left(\frac{15}{21}-\frac{5}{21}\right)+\frac{3}{4}\)

\(=\frac{6}{7}\div\frac{10}{21}+\frac{3}{4}\)

\(=\frac{6}{7}\times\frac{21}{10}+\frac{3}{4}\)

\(=\frac{126}{70}+\frac{3}{4}\)

\(=\frac{504}{280}+\frac{210}{280}\)

\(=\frac{714}{280}\)

\(\left(6-\frac{14}{15}\right).\frac{50}{38}-\frac{8}{18}\)

\(=\left(\frac{90}{15}-\frac{14}{15}\right).\frac{25}{19}-\frac{4}{9}\)

\(=\frac{76}{15}.\frac{25}{19}-\frac{4}{9}\)

\(=\frac{76.25}{15.19}-\frac{4}{9}\)

\(=\frac{19.2.2.5.5}{3.5.19}-\frac{4}{9}\)

\(=\frac{20}{3}-\frac{4}{9}\)

\(=\frac{60}{9}-\frac{4}{9}\)

\(=\frac{56}{9}\)

\(\frac{4}{6}+\frac{5}{21}.\left(\frac{4}{5}-\frac{2}{6}\right)\)

\(=\frac{2}{3}+\frac{5}{21}.\left(\frac{24}{30}-\frac{10}{30}\right)\)

\(=\frac{2}{3}+\frac{5}{21}.\frac{14}{30}\)

\(=\frac{2}{3}+\frac{70}{630}\)

\(=\frac{420}{630}+\frac{70}{630}\)

\(=\frac{490}{630}\)

\(=\frac{7}{9}\)

a)137/140,b)1/7 

nhớ k mình nha!

a)137/140

b)1/4