Respostas

2013-09-27T07:59:42-03:00
A) 5/2 +3/5=
     25/10 + 6/10= 31/10

b) -13/8 +  5 /8 = - 8/8  =  -  1

c)  2/7 . ( -4/7) =
     2/7  .   -4/7= - 8/45

d) - 5/4 .  ( -4/5)
     - 5/4 . - 4/5 = 20/20 = 1

e) 5/9 : 3/7 = 5/9 . 7/3 = 35/27


a) 3/9 = x/27
    9x   =  27 . 3
    9x = 81
    x = 81/9 = 9

b)   x/ 12 = 2/6
       6  x  = 12 . 2
        x = 24/6
         x= 4

c) 10/x = 5/4
    5x = 10 . 4
    x = 40/5
     x = 8

d) 4/20 = 10/x
     4x = 20 . 10
      x = 200/4
      x= 50