Respostas

2014-05-06T17:29:40-03:00
5-x-20=5x-10-7x-> 5-20+10=5x-7x+x -> -15=-x -> x=15
1 2 1
2014-05-06T18:55:50-03:00
5 - x - 20 = 5x - 10 - 7x
- x - 5x + 7x = - 10 - 5 + 20
- 6x + 7x = - 15 + 20
x = 5
4 5 4