SOLUTION: 2x-y=4 X+y=5

2x - y = 4,    (1)
 x + y = 5.    (2)


Add the two equations. The "y"-s will cancel and you will get a single equation for only one unknown x:

2x + x = 4 + 5 = 9  ====>  3x = 9  ===>  x =  = 3.


Thus you just found one unknown, x. It is 3.


Next, to find y, substitute x= 3 into equation  (2) and get

y = 5 - x = 5 - 3 = 2.


Answer. The solution is xx = 3,  y = 2.