19/20x2/100+19/20x2/100

= [19/20+19/20]x2/100

= 38/20x2/100

= 19/500

75/76x102/100-75/76x2/100

= [102/100-2/100]x75/76

= 1x75/76

= 75/76

3x7/10+7/10x5+2x7/10

= [3+5+2]x7/10

= 10x7/10

= 7

giá trị biểu thức 

2/5+2/3x3/4

= 2/5+1/6

= 17/30

1/2x1/3-1/8

= 1/6-1/8

= 1/24

[1/2+1/3]:3/9

= 5/6:3/9

= 5/2

                       nhớ tick cho tớ nhé

rùi đó

a: \(2\dfrac{2}{10}=2,2\)

\(4\dfrac{31}{100}=4,31\)

9/10=0,9

51/10=5,1

75/100=0,75

125/100=1,25

1075/1000=1,075

\(14\dfrac{17}{100}=14,17\)

b: 1/2=0,5

3/4=0,75

4/5=0,8

5/8=0,625

\(2\dfrac{1}{2}=2,5\)

\(3\dfrac{1}{4}=3,25\)

\(1\dfrac{3}{5}=1,6\)

\(4\dfrac{3}{8}=4,375\)

A=1/4 - 3/5 + 75/100

A=25/100-60/100+75/100

A=\(\frac{25-60+75}{100}\)

A=40/100

A=2/5

\(A=\frac{1}{4}-\frac{1}{3}+\frac{75}{100}\)

\(A=\frac{1}{4}-\frac{1}{3}+\frac{3}{4}\)

\(A=\left(\frac{1}{4}+\frac{3}{4}\right)-\frac{1}{3}\)

\(A=0-\frac{1}{3}\)

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

_Chúc bạn học tốt_

kết quả là -2/5

Tham khảo:

\(\dfrac{4}{7}-\dfrac{1}{3}< \dfrac{1}{2}-\dfrac{2}{9}\)

\(\dfrac{125}{100}-\dfrac{48}{64}< \dfrac{6}{7}-\dfrac{14}{28}\)

\(\dfrac{7}{5}-\dfrac{22}{25}=\dfrac{1}{5}+\dfrac{4}{10}\)\(\dfrac{45}{75}+\dfrac{22}{33}>\dfrac{4}{5}+\dfrac{4}{6}\)

\(\frac{1}{3}+\frac{1}{4}+\frac{1}{5}+\frac{8}{10}+\frac{26}{39}+\frac{75}{100}\)
\(=\frac{1}{3}+\frac{1}{4}+\frac{1}{5}+\frac{4}{5}+\frac{2}{3}+\frac{3}{4}\)
\(=\left(\frac{1}{3}+\frac{2}{3}\right)+\left(\frac{1}{4}+\frac{3}{4}\right)+\left(\frac{1}{5}+\frac{4}{5}\right)\)
\(=1+1+1\)
\(=3\)

1/3 + 1/4 + 1/5 + 8/10 + 26/39 + 75/100

= 7/12 + 1/5 + 8/10 + 26/39 +75/100

= 47/60 + 8/10 + 26/39 + 75/100

= 19/12 + 26/39 + 75/100 

= 52/ 117 + 75/100

= 559/400

a) 1 phần 2 = 5 phần 100 = 5 %

b) 3 phần 5 = 6 phần 100 = 6 %

a,Ta có:\(\frac{1}{2}=\frac{1\times50}{2\times50}=\frac{50}{100}=50\%\)

b,\(\frac{3}{5}=\frac{3\times20}{5\times20}=\frac{60}{100}=60\%\)

Vậy...........