1) x pretul initial
a cheltuit 30% inseamna:30x/100
rest:x-30x/100=(100x-30x)/100=70x/100
a cheltuit 2/7 din rest inseamna: 70x/100·2/7 simplificam cu 7=20x/100
rest:70x/100-20x/100=50x/100
50x/100=1800
50x=1800·100
x=180000/50
x=3600 lei pretul initial
verificare
3600·30/100=1080 lei a cheltuit
3600-1080=2520 lei rest
2520·2/7=720 lei a cheltuit
2520-720=1800 lei rest
2) x+y=156
x/y=5/7
7x=5y
x=5y/7 inlocuim in prima relatie
5y/7+y=156
(5y+7y)/7=156
12y/7=156
y=156·7/12
y=91
x=5·91/7
x=65
