Question 652262
x+2y=200
x=y+50

if x + 2y = 200, then let's solve it for x... 

x = 200 - 2y (subtracted 2y from both sides)

Now we have two "x +" equations"

x = y + 50
x = 200 - 2y

If x equals two things, those two things equal each other (transitive property)

y + 50 = 200 - 2y

3y + 50 = 200 (added 2y to both sides)

3y = 150 (subtracted 50 from both sides)

y = 50.

if y = 50, sub 50 back in for y into either of the two original equations (how about both to check?)

x + 2(50) = 200
x + 100 = 200
x = 100

x = 50 + 50
x = 100

it's the same, so x = 100, y = 50
The lines cross at (100, 50)