Question

qual o valor de x na proporcao (x-3)/18=1/2 ?

Answer 1

 (x-3)/18=1/2 
(x-3)         1
------ =   ------
18            2
Multiplica em cruz
2(x-3) = 18 . 1
2x - 6 = 18
2x = 18 + 6
2x = 24
x= 24 :2
x=12