Solve the following system of equations graphically.. x + y - 4 = 0. x - y = 0. the solution lies in quadrant . i. ii. iii. iv

Add them together
2x-4=0
2x=4
x=2

2-y=0
y=2
(2,2)
in quadrant 1

We may add the equations to find the value of the x first,
                                            x + y = 4
                                 +         x - y = 0
The sum would be 2x = 4 which gives the value of x as 2. Substitute this value to any of the equations to solve for y. The value of y is 2. Thus, the solution of the system is (2, 2) which is in the Quadrant 1. 

The correct answer is $90