x+ y=450
1,2x + 1,1y=515
--------------------------
din prima formula
x=450-y
1,2x + 1,1y=515
inlocuim x din 1 formula in a 2
x=450-y
1,2(450-y) + 1,1y=515
-------------------------------------
x=450-y
540 - 1,2y + 1,1y=515
------------------------------
x=450-y
- 0,1y=515 - 540
------------------------------
x=450-y
-0,1y=-25
------------------
x=450-y
y=25/0,1
-------------
x=450-y
y=250
----------
x=450-250
y=250
--------------
x=200
y=250.