fie x suma initiala
1 zi : 2x/4+7 = x/2+7
2 zi : (x/2+7)3/7+4
3 zi : 3,92
x/2 + 7 + (x/2+7)3/7+4+3,92 = x
(x+14)/2+(x+14)*3/2*7 + 7,92 = x
(7x+98)/14 + (3x+42)/14 + 110,88/14 = x
7x+98+3x+42+110,88 = 14x
4x = 250,88
x=62,72
1 zi : 38,36
2 zi : 20,44
3 zi : 3,92
suma : 62,72