Răspunsuri

2014-08-28T23:43:47+03:00
A - 10 + (a - 10)* 40/100 = a/2
a - 10 + (a - 10) * 2/5 = a/2
a - 10 + 2a/5 - 20/5 = a/2
10a - 100 + 2a - 40 = 5a
10a + 2a - 5 a = 100 + 40
7a = 140
a = 140/ 7
a = 20 lei

2014-08-29T00:08:54+03:00
Notam cu x suma de bani.
40/100*(x-10)=2/5*(x-10)=(2x-20)/5
x-10-(2x-20)/5=x/2 inmultim relatia cu 10
10x-100-4x+40=5x
6x-60=5x
6x-5x=60
x=60