Respostas

2014-05-21T11:16:46-03:00
A)3/10=x/30
10x=90
x=90/10
x = 9

b) )4/20=x/5  
20x = 200
x = 200/20
x=10

c) 
7/12=14/x
7x=168
x = 168/7
x = 24

d) 
18/12=3/x
18x = 36
x = 36/18
x = 2