Respostas

2013-09-18T13:49:37-03:00
25     100%

 x       80%

25*80
--------  = 20
100
1 5 1
2013-09-18T13:51:31-03:00
25 ----------- 100%
 x  ------------ 80%
100x = 25.80
100x = 2000
x = 2000/100
x = 20 horas
80% de 25 horas é 20.