Question

1.Calcule x , nas proporções

a)x/2=30/4
b)4/5=x/20
c)20/4=x/2
d)8/32=2/x
e)6/x=3/9

2.Calcule a razão entre :
a)21 e 14
b)15 e 12
c)18 e 12
d)20 e 8

Answer 1

a)x/2=30/4
 x   =  30
----     -----
  2        4

4x = 2.30
4x = 60
x = 60/4
x = 15

*************************
b)4/5=x/20

 4      =  x
------     ------
  5         20

4.20 = 5x
80 = 5x
5x = 80
x = 80/5
x = 16

******************************
c)
20/4=x/2

20    =  x
------    -----
  4         2

5 =  x
      -----
        2

5.2 = x
10 = x
x = 10

***********************
d)
8/32=2/x

  8     =   2
-----       -----
 32          x

8x = 2.32
8x = 64
x = 64/8
x = 8

***********************

e)
6/x=3/9

 6         3
----  =  ---- 
 x          9

6.9  =  3x
54 = 3x
3x = 54
x = 54/3
x = 18

¨¨¨¨¨¨¨¨¨¨¨¨¨¨¨¨¨¨¨¨¨¨¨¨¨¨¨¨
a)21 e 14
 
 21  (:7)         3
-----         =   -----
 14   (:7)        2

************************
b)15 e 12

 15   (:3)         5
-----         =  ------
 12   (:3)         4

****************************
c)18 e 12

18  (:6)        3
------      =  ------
 12 (:6)        2

****************************
d)20 e 8

20   (:4)       5
-----        =  -----
  8   (:4)       2

***************************

Answer 2

1°

a) x/2 = 30/4
    4x = 30.2
    4x = 60
    x = 60/4
    x = 15

b) 4/5 = x/20
   5x = 4.20
   5x = 80
   x = 80/5
   x = 16

c) 20/4 = x/2
    x/2 = 5
    x = 5.2
    x = 10

d) 8/32 = 2/x
    8x = 32.2
    8x = 64
    x = 64/8
    x = 8

e) 6/x = 3/9
    3x = 9.6
    3x = 54
    x = 54/3
    x = 18

2°

a) 21 e 14

21/14 = 3/2

b) 15 e 12

15/12 = 5/4

c) 18 e 12

18/12 = 3/2

d) 20 e 8

20/8 = 5/2