we have the system
x+y=8 -----> equation A
x-y=4 ----> equation B
Solve the system by graphing
Remember that the solution is the intersection point both graphs
so
using a graphing tool
see the attached figure
the solution is the point (6,2)
Step-by-step explanation
To graph, the lines find out the intercepts
x+y=8 -----> equation A
x-intercept (value of x when the value of y=0)
For y=0
x+0=8
x=8
the x-intercept is (8,0)
y-intercept (value of y when the value of x=0)
For x=0
0+y=8
y=8
y-intercept is (0,8)
x-y=4 ----> equation B
x-intercept ---------> (4,0)
y-intercept -------> (0,-4)
To graph, each line, plot the intercepts and join the points to graph the line
see the attached figure