solve using substitution or elimination

Question

x=2y x+y=3

Answer 1

To solve by substitution, you solve one part of the system for one variable and then substitute the value for the variable into the other part of the system.  In this case we already know the value for x is 2y. so we can plug in 2y where we see x in the second equation

x+y=3

Substitute

2y+y=3

now we can solve for y

add 2y and y to get

3y=3

divide both sides by 3

y=1

Now to find the number value of x we plug the number value of y back in to either of the original equations like this

x=2y

substitute in the 1

x=2*1

then solve for by multiplying 2 times 1

x=2

So our solutoins are x=2 and y=1

Answer 2

X=2 y=1