9 + 9 = 18

8 + 8 =16

7 + 7 =14

5 + 5 =10

5 + 6 + 7 + 8 +9 = 33

9+9=18

8+8=16

7+7=14

5+6+7+8+9=35

5

10

15

20

25

30

35

40

45

1+1+1+1+1=...?

2+2+2+2+2=...?

3+3+3+3+3=...?

4+4+4+4+4=4x5=20

5+5+5+5+5=5x5=25

6+6+6+6+6=6x5=30

7+7+7+7+7=7x5=35

8+8+8+8+8=8x5=40

9+9+9+9+9=9x5=45

8+1=9

1+8=9

9-8=1

9-1=8

7+2=9

2+7=9

9-7=2

9-2=7

6+3=9

3+6=9

9-6=3

9-3=6

5+4=9

4+5=9

9-5=4

9-4=5

Chúc bạn học giỏi nha!!!!

K cho mik với nhé 

8+1=9

1+8=9

9-8=1

9-1=8

7+2=9

2+7=9

9-7=2

9-2=7

6+3=9

3+6=9

9-6=3

9-3=6

5+4=9

4+5=9

9-5=4

9-4=5

7+9+7-9+10-1+98

=14+9+98

=23+98

=121

ok k nhé @@@@@@@@@@@@@@@

ok trả lởi chính xác

1+1+1+1+1=5

1+1+1+1+1=5

2+3+4+2+3+4=18

5+6+7+5+6+7+8=44

9+9+9+9+1+1+1+1=40

12

14

16

19

20

6 + 6 = 12

7 + 7 = 14 

8 + 8 = 16

9 + 9 = 18

10 + 10 = 20

hok tốt

9 + 1 = 10 

8 + 2 = 10 

7 + 3 = 10

12 - 2 = 10

12 + 7 - 9 = 10

9+1=10

8+2=10

7+3=10

12-2=10

12+7-9=10

chuc em thanh cong trong hoc tap 

good luck to you !

a)2

b)75/37

c)0

d)8/27

e)7/19

f)4

ok

a) \(\frac{2}{9}+\frac{1}{5}+\frac{7}{9}+\frac{4}{5}=\left(\frac{2}{9}+\frac{7}{9}\right)+\left(\frac{1}{5}+\frac{4}{5}\right)= 1+1=2 \)

b) \(\frac{19}{37}+\left(1+\frac{19}{37}\right)=\left(\frac{19}{37}-\frac{19}{37}\right)+1=0+1=1\)

c) \(\frac{9}{8}-\left(\frac{17}{7}-\frac{3}{7}\right)+\frac{7}{8}=\frac{9}{8}+\frac{7}{8}-\left(\frac{17}{7}-\frac{3}{7}\right)=2-2=0\)

d) \(\frac{3}{5}\times\frac{8}{27}\times\frac{5}{3}=\frac{3}{5}\times\frac{5}{3}\times\frac{8}{27}=1\times\frac{8}{27}=\frac{8}{27}\)

e) \(\frac{7}{19}\times\frac{1}{3}+\frac{7}{19}\times\frac{2}{3}=\frac{7}{19}\times\left(\frac{1}{3}+\frac{2}{3}\right)=\frac{7}{19}\times1=\frac{7}{19}\)

f) \(\frac{12}{5}\times4-4\times\frac{7}{5}=4\times\left(\frac{12}{5}-\frac{7}{5}\right)=4\times1=4\)