The area of a rectangle is 1372 m². Such that the width is $\frac{4}{7}$the length. Find the perimeter of the rectangle ? ( m )

Toan Aunt buys five tables and 7 chairs with the total cost is 3 010 000 vnd. The price of a table is 170 000 vnd more than the price of a chair. If  buying one table and 2 chairs, how much is it totally ? (vnd )

There are 5 natural numbers. If you add five numbers together and then the result divided by 5, the quotient is 138. To arrange in order of increasing. Then hen adding three fist number together and divided by 3, the quotient is 127. If adding three last number and divided by 3, the quotient is 148. What is the number in the middle ?

An has four stamps with type 1000vnd and three stamps type 2000vnd. Using one or many different stamps with the following value. How many ways does An have to pay money by sticking stamp on the envelope ?

Three chickens and two ducks weigh 32 kilograms ; four chikens and 3 ducks weigh 44 kilogram. The chickens have the same weigh and the ducks have the same weight. How much do two chickens and one duck weigh ?

There are three number A, B, C such that if two numbers of them adds to each other, the result is: 126 , 140 , 158. Find the greatest number and smallest number?

An sold some of apples to receive some money. If An sold 10 apples more with the same money before, the price of each apple is 200vnd. If An sold less than 10 apples, the price of each apple incresed by 400vnd. Find the price of each apple ?

Calculate : D = 2 + 5 + 9 + 14 + ....+ 4949 + 5049

Calculate : 1+ 3 + 6 + 10 +...+ 4851 + 4950

Calculate : 6 + 16 + 30 + 48 + ... + 19600 + 19998

Compare A and B such that :

A = $\frac{1\times 2+2\times 4+3\times 6+4\times 8+5\times 10}{3\times 4+6\times 8+9\times 12+12\times 16+15\times 20}$

Và B =$\frac{11111}{66665}$

Calculate quickly : A = $\frac{1}{1\times 6\times 6}+\frac{1}{2\times 9\times 8}+\frac{1}{3\times 12\times 10}+...+\frac{1}{98\times 297\times 200}$

( Write the result as a/b )

Calculate : $\frac{1}{1+2}+\frac{1}{1+2+3}+\frac{1}{1+2+3+4}+...+\frac{1}{1+2+...+2009}$

( Write the result as a/b )

Find A such that :

$(1-\frac{1}{3})\times (1-\frac{1}{6})\times (1-\frac{1}{10})\times (1-\frac{1}{15})\times ....\times (1-\frac{1}{780})\times A=1$

( Write the result as a/b )

Calculate :

$\frac{5}{27}+\frac{5}{27\times 2}+\frac{1}{6\times 3}+\frac{1}{3\times 9}+\frac{5}{3\times 63}+\frac{5}{63\times 4}+\frac{5}{4\times 81}+\frac{1}{81}$

( Write the result as a/b )