How do I do this..............

2x + y = 8
x + y = 4

The lines intersect at

These are simultaneous equations, they can be solved by addition.

you need first to get rid of y or x to find the value of the other one:

I'll multiply the first equation by -1 to get red of y:
so, the two equations are
-2x-y = -8
x + y = 4

now, add the two equations you'll get
-x = -4 ---------> x = 4

now, substitute the value of x in any of the equations to get the value of y
4+y = 4 y =0

so, the lines intersect at (4,0)

At the point they intersect, both are true for the same value of x and y , thus it is OK to combined the two equations.

2x + y = 8 .......i
x + y = 4..........ii

subtract ii from i

x + 0 = 4
x= 4

substitute in ii
4 + y = 4
y = 0

(4,0)

mutiply the second equation by -1 u should get -x-y=-4 then add it to the 1st equation and u should get x=4 so u substitute it into any equation the second is easier so it would be 4+y=4 then subtract 4 from both sides so y=0

First put it in its original form:

y = -2x + 8 and
y = -x + 4

Then draw the line.