Gọi số đó là ab ( a và b < 10 và a > 0 ) ta có :

ab = ba x 4,5

a x 10 + b = ( b x 10 + a ) x 4,5

a x 10 + b = b x 45 + a x 4,5

a x 5,5 = b x 44 

a = b x 8 

Vì a và b < 10 và a > 0 nên  b x 8 < 10 . Vậy b = 1 , a = 8

Số phải tìm là : 81

người đó làm 1 sản phẩm hết số thời gian là:

(12-8):5=0,3(giờ)

người đó làm 6 sản phẩm hết số thời gian là:

0,3x6=1,8(giờ)

ĐS:1,8 giờ

V.

1. The children..were playing...... (play) happily in the park when i found them.

2. I'll come and see you before i ..leaving.... (leave) for the United States.

3. As soon as Martina saw the fire, she .had telephoned....... (phone) the fire department.

4. He'll take a dog out for a walk as soon as he ..finishes.....(finish) his work.

VI. chuyển câu có nghĩa tương đương. sử dụng câu bị động

1. they cancelled all flights because of fog.

=> All flights were cancelled because of dog

2. Bill is using the computer at the moment.

=> The computer is being used by him at the moment

3. they pay designers a lot of money.

=> Designers are paid a lot of money

4. when did they decorate your kitchen?

=> When was your kitchen decorated?

5. we have to test these products.

=> These products have to be tested

6. The situation is serious. We must do something before it's too late.

=> The situation is serious. Something must be done before it's too late

Choose the sentences with the correct order .

1. trip/we/excited/at/our/feel/about/countryside/the/to/the/weekend.

A. We feel excited to out trip about the countryside at the weekend .

B. We feel excited about the trip to the coutryside at our weekend .

C. We feel excited about our trip to the coutryside at the weekend .

D. We feel excited about the trip at the coutryside to our weekend .

2.a/tent/putting/not/is/building/as/up/hard/as/house/a.

A.Putting up a house is not as hard as building a tent .

B.Putting up a tent is not as hard as building a house.

C.Putting up a tent is as not hard as building a house.

D.Putting a tent is not as hard as building up a house.

3.money/I/thann/happiness/that/more/is/think/important.

A.I think happiness that is more important that money

B.I think that happiness is more important that money

C.I think that happiness more is important that money

D.I think that happiness is important more that money

số lớn là

1991 : (1990 + 1) x 1990 = 1990

số bé là

1991 - 1990 = 1

neu minh la thanh thi se xoa nick olm cua bn ngay lap tuc

10 chu so 0

câu trả lời là 7-6=1