Question

Use addition or substitution to find the value of y for this set of equations.
12x - 5y = 30
y = 2x - 6

Answer 1

we already know that y = 2x - 6. So sub 2x - 6 in for y in the first equation...
12x - 5y = 30
12x - 5(2x - 6) = 30
now just distribute the -5 through the parenthesis.
combine like terms.
get the x's on one side.
solve for x.
once x is found sub it back into either of the equations to find y.
you can then check it by subbing in your known values into either of the original equations and if it comes out equal, your answers are correct. If it doesn't come out equal, then there is a mistake somewhere.