1/Tính nhanh

a)  2.4.5.25.28

= (2.5) . (4.25) . 28

= 10 . 100 . 28

= 1000 . 28

= 28000

b) 45.54+45.23-35.77

= 45.(54 + 23) - 35.77

= 45.77 - 35.77

= (45 -35) . 77

= 10 . 77

= 770

2/Tìm x:

6.x + 108 : 9 = 24

6.x + 12 = 24

6.x = 24 - 12

6.x = 12

x = 12 :6 

x = 2

Vậy x=2

*Dấu chấm là dấu nhân nha *

watches

to

plays 

Chọn đáp án đúng: 1.What do you like doing in your ( empty/spare) time? 2. Kate usually (passes/spends) most of her time reading. 3. Tìm has a very interesting (fun/hobby), he builds small boats.

16.have lived 

17.has seen

18.left

19.has written/ hasn't finished

20.won

21.lost

22.decided

23.donated

24.has taught

25.How long have you learnt

D

Giải :

Cách 1:

(2/5 + 1/2) .1/4

= 9/10 . 1/4

= 9/40

Cách 2:

(2/5+1/2).1/4

= 2/5 . 1/4 + 1/2 . 1/4 

= 1/10 + 1/8

= 9/40

* Dấu chấm là dấu nhân nha *