1 What is your hobby?

2 When did you start your hobby

3 Why do you enjoy your hobby

4 How many hours a day do you spend on your hobby

5 What does Jim usually do in his free time

6 How often does he play volleyball 

7 Where does he often play volleyball

8 Who does he like to play volleyball with

I. Write questions for the underlined parts.

1. A: What is your hobby

B: My hobby is photography.

2. A:When did you started yor hobby

B: I started my hobby five years ago.

3. A:why do you enjoy your hobby

B: I enjoy my hobby because I think it’s creative.

4. A:How many hours a day fo you spend on your hobby

B: I spend two hours a day on my hobby.

5. A:What does Jim ussually do in his free time

B: Jim usually plays volleyball in his free time.

6. A:How often does he play volleyball  

B: He plays volleyball three times a week.

7. A:Where does he often play volleyball 

B: He often plays volleyball at the court near his school.

8. A:Who does he like to play with

B: He likes to play volleyball with his friends.                                                

\(\frac{a}{3}=\frac{b}{5}=\frac{3a}{9}=\frac{b}{5}=\frac{3a-b}{9-5}=\frac{17,2}{4}=4,3\)

\(\frac{a}{3}=4\Rightarrow a=12,9\)

\(\frac{b}{5}=4,3\Rightarrow b=21,5\)

a+b=12.9+21.5=34.4

cảm ơn

\(\frac{a}{b}=\frac{3}{5}\Rightarrow\frac{a}{3}=\frac{b}{5}=\frac{3a}{9}=\frac{b}{5}\)

Áp dụng tính chất của dãy tỉ số bằng nhau ta có:

\(\frac{3a}{9}=\frac{b}{5}=\frac{3a-b}{9-5}=\frac{17,2}{4}=4,3\)

\(\frac{a}{3}=4,3\Rightarrow a=4,3.3=12,9\)

\(\frac{b}{5}=4,3\Rightarrow b=21,5\)

\(\Rightarrow a+b=12,9+21,5=34,3\)

có a:b=3:5

'=>\(\frac{a}{3}\)=\(\frac{b}{5}\)

=>\(\frac{3a}{9}\)=\(\frac{b}{5}\)

Áp dụng tính chất dãy tỉ số bằng nhau

\(\frac{3a}{9}\)=\(\frac{b}{5}\)=\(\frac{3a-b}{9-5}\)=\(\frac{17.2}{4}\)=4.3

\(\frac{3a}{9}\)=4.3=>3a=38.7=>a=12.9

\(\frac{b}{5}\)=4.3=>b=21.5

=>a+b=12.9+21.5=34.4

Ta có :       a : b = 3 : 5

=>  a/3 = b/5

Áp dụng tính chất dãy tỉ số bằng nhau :

a/3 = b/5 = ( b - a) / ( 5 - 3 ) = -16/2 = -8

=> a = -21

     b = -40

a:b=3:5

\(\Rightarrow\frac{a}{3}=\frac{b}{5}\) và 3a-b=17,2

Theo tính chất của dãy tỉ số bằng nhau, ta có:

\(\frac{a}{3}=\frac{b}{5}=\frac{a-b}{3-5}=\frac{3a-b}{3.3-5}=\frac{17,2}{4}=4,3\)

suy ra:

\(\frac{a}{3}=4,3\Rightarrow a=4,3.3=12,9\)

\(\frac{b}{5}=4,3\Rightarrow b=4,3.5=21,5\)

khi đó a+b=12,9+21,5=34,4

8,4 nha .

ta có a:b=3:5=>\(\frac{a}{3}=\frac{b}{5}\) và 3a-b=17,2

=>\(\frac{a}{3}=\frac{b}{5}=>\frac{3a}{9}=\frac{b}{5}\)

áp dụng tính chất dãy tỉ số bằng nhau ta có

\(\frac{3a}{9}=\frac{b}{5}=\frac{3a-b}{9-5}=\frac{17,2}{4}=\frac{43}{10}\)

*\(\frac{a}{3}=\frac{43}{10}=>a=\frac{4}{10}.3=\frac{129}{10}=12,9\)

*\(\frac{b}{5}=\frac{43}{10}=>b=\frac{43}{10}.5=21,5\)

a+b=12,9+21,5=34,4

vậy a+b=34,4

a:b đc 5 dư 3 => a= 5b+3

                    => 5b= a-3

                    => b/(a-3) = 1/5

vậy tỉ số là 1/5

Ta có : a:c được 5 và dư 3

Nên :a=5b+3

Hay :5b=a-3

Suy ra : \(\frac{b}{a-3}=\frac{1}{5}\)

Vậy tỉ số của b và a-3 là :\(\frac{1}{5}\)

a: b được 5 dư 3 = > a = 5b + 3

                                = > 5b=a-

                                   => b/(a-3) = 1/5

- Xét: a : b = 9 : 4 \(\Rightarrow\frac{a}{9}=\frac{b}{4}\)\(\Rightarrow\frac{a}{45}=\frac{b}{20}\)

       b : c = 5 : 3 \(\Rightarrow\frac{b}{5}=\frac{c}{3}\)\(\Rightarrow\frac{b}{20}=\frac{c}{12}\)    

=> \(\frac{a}{45}=\frac{b}{20}=\frac{c}{12}\)

- Đặt: \(\frac{a}{45}=\frac{b}{20}=\frac{c}{12}=k\Rightarrow\hept{\begin{cases}a=45.k\\b=20.k\\c=12.k\end{cases}}\)

-Thay a = 45.k, b = 20.k , c = 12.k vào \(\frac{a-b}{b-c}\) ;ta có: 

\(\frac{a-b}{b-c}=\frac{45.k-20.k}{20.k-12.k}=\frac{25.k}{8.k}=\frac{25}{8}\)

Vậy \(\frac{a-b}{b-c}=\frac{25}{8}\)