Question

y=2x+1
3y-3x=9

Answer 1

substituting first eqn into second

3(2x + 1) - 3x = 9
6x + 3 - 3x = 9
3x = 9 - 3
x = 6/3
x = 2

Answer 2

You plug y = 2x +1 into 3y - 3x = 9 to get:

3(2x+1) -3x = 9

which simplifies to

3x +3 = 9
3x = 6
x = 2

then you take your x value and plug it back in to the original y equation to get

y = 2(2) +1
y = 5

so x=2 and y = 5

Answer 3

Now put x = 2 in first eqn

y=2x+1
y = 2(2) + 1
y = 5


so solution (x,y) = (2,5)