giàu r , chậm thôi :>

231 x 87 + 32 x 231 - 19 x  231

= 231 x (87 + 32 - 19)

= 231 x 100

= 23100

C

1. I want to pass the exam so I need to work hard .

2. He easily won to the race because he was the best candidate .

3. She went to the shop.However, She couldn't find anything she liked .

4. He was angry with her.Therefore, He didn't say a word .

5. He is out-going and helpful .

6. The TV set I have now is broken.Therefore,I need a new one.

7. I turned on the heater because it was cold in here.

8. We have to do the shopping and we have to clean the house as well.

9. The history test is easy but it is long.

10. Fast food is convenient but it is bad for health.

35 phút

a. x + 3/7 = 2/5 : 18/35

    x + 3/7 = 7/9

    x          = 7/9 - 3/7

    x          = 22/63

b. x nhân 5/9 = 4/5 - 1/3

   x nhân 5/9 = 7/15

   x                = 7/15 : 5/9

   x                = 21/25

Giải thích ????

= 123

12 x 3 + 12 x 8 - 12

= 12 x 3 + 12 x 8 - 12 x 1

= 12 x ( 3 + 8 - 1)

= 12 x 10

= 120