\(\frac{18}{27}-\frac26\)

\(=\frac23-\frac13=\frac{2-1}{3}=\frac13\)

\(\frac{37}{12}-3=\frac{37}{12}-\frac{36}{12}=\frac{37-36}{12}=\frac{1}{12}\)

\(5-\frac{14}{3}=\frac{15}{3}-\frac{14}{3}=\frac{15-14}{3}=\frac13\)

\(\frac{10}{21}:\frac23=\frac{10}{21}\times\frac32=\frac{30}{42}=\frac57\)

\(\frac35:\frac34=\frac35\times\frac43=\frac33\times\frac45=\frac45\)

\(\frac25:\frac{3}{10}=\frac25\times\frac{10}{3}=\frac{20}{15}=\frac43\)

\(\frac38:\frac94=\frac38\times\frac49=\frac{12}{72}=\frac16\)

\(\frac{8}{21}:\frac47=\frac{8}{21}\times\frac74=\frac{7}{21}\times\frac84=\frac23\)

\(\frac85:\frac{15}{8}=\frac85\times\frac{8}{15}=\frac{64}{75}\)

8/27+4/5+19/27+11/15=(8/27+19/27) + (4/5+11/15)

                                    = 1+ (12/15+11/15)

                                    = 1+ 1/8/15=2/8/15

12/13+2/7+8/13+6/13+5/7=(12/13+8/13+6/13) + (2/7+5/7)

                                         = 2+ 1

                                         =3

Ý a có thể bạn chép nhầm 4/5 rồi

= 2 + 1=3 nhé bạn

a: =(8/27+19/27)+(4/15+11/15)=1+1=2

b: =(12/13+8/13+6/13)+(2/7+5/7)=2+1=3

BÀI 1:

a)    \(\frac{4}{5}+\frac{3}{8}+\frac{1}{4}\)

\(=\frac{32}{40}+\frac{15}{40}+\frac{10}{40}\)

\(=\frac{32+15+10}{40}\)\(=\frac{57}{40}\)

b)    \(\frac{5}{9}+\frac{2}{3}+\frac{1}{2}\)

\(=\frac{10}{18}+\frac{12}{18}+\frac{9}{18}\)

\(=\frac{10+12+9}{18}=\frac{31}{18}\)

bài 23,, 5 nữa

2 x 5 + 5 x 7 + 9 x 3 

= 5 x ( 2 + 7 ) + 9 x 3 

= 5 x 9 + 9 x 3 

= 9 x ( 5 + 3 )

= 9 x 8

= 72

2x5+5x9+9x3                                       15:5+27:5+8:5

=9x5+(2+3)                                         =(15+8+27):5

=9x5+5                                               =50:5

=9x5+5x1                                            =10

=5x(9+1)                                             9+9x3+18:2x6

=5x10                                               =1x9+9x3+9x6

=50                                                   =9x(1+6+3)

                                                         =9x10

                                                         =90

8757577

3/4+1/2+5/8=15/8

5/9+9/8-15/28=577/504

11/30-9/25x15/27=1/6

3/4:5/8:3/10=4

a,15/8

b, 73/56

c,1/6

d,4

đúng nhé bạn

a,15/8

b, 73/56

c,1/6

d,4

(3/5+2/5)+(4/9+5/9)=1+1=2

(5/4+3/4)+(3/8+5/8)=8/4+1=8/4