Question

y=-x+6
7y=5x-42

solve for x and y

Answer 1

see this tutorial on systems of linear equations http://openstudy.com/updates/4fa7aa68e4b029e9dc388281

tell me if you dont get something and ill explain it to you

Answer 2

Notice how the second equation includes y, so replace y with the first equation:
\[7(-x+6) = 5x-42\]
Expanding:
\[-7x + 42 = 5x - 42\]
Then group terms:
\[84 = 12x\]
Divide to solve for x:
\[x=7\]
Now substitute x in any of the equations; the first is simpler, so let's start there.
\[y=-(7)+6\]
Therefore y=-1
We can check this by plugging in x and y in both equations and hope these values make each equation true.

\[-1 = -7 + 6\]
\[7(-1)=5(7)-42\]

Both left and right sides are equal; therefore the solutions are x=7, y=-1.