Given the system of equations, what is the x-coordinate of the solution? y = 3 - 1/2x 3x + 4y = 1 a) 22 b) -17/2 c) -11

Choice C) -11



Explanation:

The first equation given is y = 3 - 1/2x
In other words, y is the same as 3 - 1/2x. 
We can replace y in the second equation with 3 - 1/2x
This is known as substitution (think of a substitute teacher who is a temporary replacement for your teacher)

Doing this leads to...
3x+4y = 1
3x+4*y = 1
3x+4*( y ) = 1
3x+4*( 3 - 1/2x ) = 1 <<--- y has been replaced with 3-1/2x
3x+4*(3) +4*(-1/2x) = 1
3x+12-2x = 1
3x-2x+12 = 1
x+12 = 1
x+12-12 = 1-12 <<-- subtracting 12 from both sides
x = -11
Which is why the answer is choice C) -11