28(x+y)=1078
14x+30y=764
28(x+y)=1078⇒x=(1078-28y)/28
14x+30y=764 ⇒ x=(764 -30y)/14
le egalam⇒
(1078-28y)/28 =(764 -30y)/14
1078 -28y =764×2 -30y×2
1078 -28y = 1528 -60y
-28y +60y =1528 - 1078
32y = 450
y =14,0625 lei costa un bilet la film 3D
x =(764 -30y)/14=(764-421,875)/14=342,125/14
x = 24,4375 lei costa un bilet la film 2D
verificare
28 ×(x+y)=1078
28×(24,4375 + 14,0625) =
28×38,5 =1078
1078 =1078
