Số bi của Lan là:

(64 - 12) : 2 = 26 (viên)

Đáp số: 26 viên bi

\(\dfrac{\dfrac{3}{5}.7^2-3.5^6+\dfrac{3}{5}.3^9}{\dfrac{3}{4}.7^2-\dfrac{3}{4}.5^7+\dfrac{3}{4}.3^9}\)

\(=\dfrac{\dfrac{3}{5}.7^2-3.5^6+\dfrac{3}{5}.3^9}{\dfrac{5}{4}\left(\dfrac{3}{5}.7^2-3.5^6+\dfrac{3}{5}.3^9\right)}\)

\(=\dfrac{1}{\dfrac{5}{4}}\)

\(=\dfrac{4}{5}\)

105 x 3 + 35 x 89 + 70

= 35 x 3 x 3 + 35 x 89 + 35 x 2

= 35 x 9 + 35 x 89 + 35 x 2

= 35 x (89 + 9 + 2)

= 35 x 100

= 3500

20,23 x 14 + 40,46 x 16 + 60,69 x 18

= 20,23 x 14 + 20,23 x 2 x 16 + 20,23 x 3 x 18

= 20,23 x 14 + 20,23 x 32 + 20,23 x 54

= 20,23 x (14 + 32 + 54)

= 20,23 x 100

= 2023

Ta có:

\(a=\dfrac{7}{8}b\)

\(b=\dfrac{6}{5}c\Rightarrow c=b\div\dfrac{6}{5}=\dfrac{5}{6}b\)

\(a+b+c=130\)

\(\dfrac{7}{8}b+b+\dfrac{5}{6}b=130\)

\(\dfrac{65}{24}b=130\)

\(b=130\div\dfrac{65}{24}\)

\(b=130\times\dfrac{24}{65}\)

\(b=48\) (học sinh)

\(\Rightarrow a=48\times\dfrac{7}{8}=42\) (học sinh)

\(\Rightarrow c=130-48-42=40\) (học sinh)

Đáp số: Lớp a: 42 học sinh

             Lớp b: 48 học sinh

             Lớp c: 40 học sinh

1 - 100 = -99

1. boots

2. picture

3.

1) c

2) b

3) d

4) a

5) e

4. Hieu's

5. Rose's

6. A

7. B

8. B

9. A

10. D

11. He is wearing black pants.

12. What color is your shirt?

13. Are these your pajamas?

14. Whose glasses are these?

15. She is wearing a green scarf.

Y : 0,25 + Y : 0,5 + Y + Y : 0,01

= Y x 4 + Y x 2 + Y x 1 + Y x 100

= Y x (4 + 2 + 1 + 100)

= Y x 107

Vô ý.

46. We haven't spoken to each other for a week.

47. Lan didn't remember her birthday, and neither did I.

48. I promise I will visit you when I come to Sa Pa.

49. Mr.Ba's car is the biggest in the company.

50.  Students don't need to wear uniforms today.