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2008-01-03 5:53 am
1)The sum of two consecutive integers is 85 .find the integer .
1)If 6 is subtracted from a number .the result is equal to one-third od the number .Find the number
3)John is 5 years older than his brother David .The sum of their ages is 35 .How old is David?
4)12(x-3)=7x-6
5)6y-1/2=2y-9
6)o.6y-0.3=0.5y
7)1/y-1/2y=1/10
8)Afather's age is 5 times of his son .If the sum of their ages is 48 .find the son 's age

回答 (2)

2008-01-04 2:04 am
ans:
1.
let x&(x+1) be the integers.
        x+(x+1)=85
             2x=84
              x=42
∴The integers are 42&43.

2.
let x be the number.
              1
         x-6=---(x)
              3
         3x-18=x
            2x=18
             x=9
∴the number is 9.

3.
let x years old be the age of david.
           x+(x+5)=35
                2x=30
                 x=15
∴david is 15 years old.

4.
        12(x-3)=7x-6
        12x-36=7x-6
            5x=30
             x=6

5.
               1
          6y- --- = 2y-9
               2
          12y-1 = 4y-18
             8y=-17
                   17
              y=- ----
                    8

6.
          0.6y-0.3=0.5y
              0.1y=0.3
                 y=3

7.
            1      1     1
           --- - ---- = ---
            y     2y     10

            10-5=y
               y=5

8.
let x years old be the age of the son.
          x+5x=48
            6x=48
             x=8
∴the son is 8 years old.
2008-01-03 7:12 am
1)42,43
2)9
3)x+(x+5)=35
x=15
David is 15 year old
4) x=6
5)y= -8.5
6)y=0.1
7)y=5
8)x+5x= 48
x=8
參考: me


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