Two groups of workers do the same job. The first group spends 15 days to finish the job while it takes the second group 12 days. How many days do ½ of the first group and 1/5 of the second group need to finish the job?

Two workers finish a job after 16 hours working together. The first person works in 3 hours, while the second person only finishes 25% of the job. How many hours does the each person needs to finish the job working seperately?

Hoang finishes a job after 10 days working alone, while it takes Minh 15 days. Anh takes 5 times the number of days that both Hoang and Minh need to finish the job. How many hours does the second person need to finish the job working alone?

Three workers do the same job. The first person finishes it in 8 hours working alone. The third person finishes the job after 6 hours and 3 hours for the second person. How many hours does the second person need to finish the job working alone?

A and B finish a job after 3 hours working together, while C and B finish the same amount of job in 4 hours, and 2 hours for A and C. How many hours do three of them need to finish the job working together?

Two people finish a job after 6 hours working together. The first person finishes it in 10 hours working alone. How many hours does the second person need to finish the job working alone?

2 workers do the same job. The first person finishes the job after 4 hours working alone, and 6 hours for the second person. How many hours do both of them need to finish the job if they work together?

Son and Hai do the same job. Son finishes the job after 3 hours working alone, and 6 hours for Hai. How many hours do both of them need to finish the job if they work together?

3 people work in a same job. The first person finishes the job in 3 weeks. In 8 weeks, the second person finishes 3 times the job. The third person finish the 5 times amount of work in 12 weeks. How many hours are there for all three people to finish the job if they work 45 hours per week?

Find the 3 – digit numbers such that each number adds to 543 then we have a similar 3 – digit number?

The sum of three numbers is 1978. The first number is 58 more than the sum of two other numbers. If the second number decreased by 36 units then its value is equal to value of the third number. Find the three numbers ?

Calculate:

$\frac{3}{5}+\frac{6}{11}+\frac{7}{13}+\frac{2}{5}+\frac{16}{11}+\frac{19}{13}$ ?

Find x and y such that the natural number A = $\overline{1996xy}$ is divisible by  2; 5 and  9 ?

Find x, such that:

( x + 2 ) + ( x + 4 ) +  ….. + ( x + 1996 ) = 998000

Calculate:

2 x 3 x 4 x 8 x 50 x 25 x 125 ?

Write consecutively words: TO QUOC VIET NAM form a sequence:

TOQUOCVIETNAMTOQUOCVIETNAM……..

Find the 2007^th words in the sequence ?

How many even 3 – digit numbers such that divisible by 9 ? 

The sequence: 11; 14; 17; 20; …..; 68 . How many terms in the sequence ?

Find the 50^th term of the sequence:

1; 4; 7; 10; …..

How many even 4 – digit numbers such that hundreds digit is 2 that can be formed by using the digits: 0; 1; 2; 3; 4 ?

Find the sum of all the 3 – digit numbers, each number is divisible by 5 and its three digits are odd number ?

Given the two numbers $\overline{ab}$ and $\overline{ba}$ ( a > b ). Know the sum of them is a number that its the ones digits is 3 and the difference of them is a number such that its the ones digits is 7. Find a and b ? 

Find the sum of all the 3 – digit numbers, each number is divisible by 5 and its three digits are odd number ?

Given the two numbers $\overline{ab}$ and $\overline{ba}$ ( a > b ). Know the sum of them is a number that its the ones digits is 3 and the difference of them is a number such that its the ones digits is 7. Find a and b ?

We don’t have milk _______ the evening.