Help with solving systems using substitution?

http://www.regentsprep.org/regents/math/algebra/ae3/algsys.htm

Awesome so can we walk through this one question on my practice sheet?

x+y=8
y=3x
a.(4,12)
b. (2,6)
c. (1/2,3/2)
d. (-4, -12)

Wait I think it is B.Is that correct?

Yes, b is right.

so instead of y in the first equation you substitute 3 x

x + 3 x = 8
4 x = 8
x = 2
now go back and get y
y = 3 x = 3*2 = 6
so
(2,6)
yes, b

Great! Thanks Damon, and thank you Ms.Sue!

You're welcome, Lady.