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2011-06-17 2:13 am
1. If a number is multiplied by 2 and 5 is added to the product , the result is 21 . Find the number .

2. If a number is dicided by 4 and 4 is added to the quotient , the result is 17 . What is the number ?

3. Twice the sum of 2 and a number is equal to 12 . What is the number ?

4. A stone and 3 one-gram weights balance with 1 fifty-gram weights and 4 one-gram weights . What is the weight of the stone ?

5. A man is 3 times as old as his daughter . Five years ago , the man was 31 years old . What is the age of his daughter now ?

6. A woman is twice as old as her son . Four years ago , her son was 17 years old . What is the age of his mother now ?

7. The length of a rectangle is (2x+5) cm and the breadth is 6 cm . Given that the area is 66 cm2 , find x .

8. A plant grows 3.5 cm pre week . It is now 10 cm tall . How many weeks from now will the plant grow to height of 27.5 cm ?

9. Peter has y more marbles than John . John has 8 marbles and together they have 25 marbles . Find y .
更新1:

咩叫 y*2 ??

回答 (2)

2011-06-17 4:05 am
✔ 最佳答案
1) Let the no be x,
(x*2)+5=21
x=8

2) Let the no be y,
(y/4)+4=17
y=52

3)Let the no be y,
2(2+y)=12
y=4

4)Let the weight of stone be z,
z+3=50+4
z=51

5)Let daughter's age be t,
31=(t*3)-5
t=12

6) Let mother's age be r,
17=(r/2)-4
r=38

7) (2x+5)*6=66
x=3

8) Let the no of weeks be t,
3.5t=27.5-10
t=5

9) John=8
Peter=8+y
8+y+8=25
y=9

2011-06-16 20:07:02 補充:
If u goona ask questions about maths next time, post them on the maths page... there are many experts!

2011-06-16 22:15:26 補充:
y*2 = y X 2
參考: exactly correct~
2011-06-17 5:40 pm
To :回答者: seeker
No offence; mother’s age should be 42.

6) Let mother's age be r,
17 = (r/2) - 4
17 + 4 = r/2
21 = r/2
r = 21 x 2
r = 42


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