18x + 15 - y = 0
5y = 90x + 12
step by step and i'll mark you brainliest

Both equations cancel each other out

Step-by-step explanation:

18x + 15 - y = 0

5y = 90x + 12

You want to use the substitution method for this system of equations because the y can easily be isolated in the first equation. Just add y to both sides so that the y variable is isolated. You will have y = 18x + 15. Substitute that equation into the second equation and solve for x. So you will have           5(18x + 15) = 90x + 12.

Use the Distributive Property to get rid of the parenthesis.

90x + 75 = 90x + 12. Subtract 90x from both sides. There is no value for x as the 90x's cancel each other out. And we all know that 75 does not equal 12

if the eqn of the parabola is f(x) = (x-4)(x+2), we need to mult. this out to find the coordinates of the vertex.

then f(x) = x^2 + 2x - 4x - 8, and f(x) = x^2 - 2x - 8.

one way in which you can find the vertex is to calculate x = -b / (2a).   here, that comes to

        )

x = = 1.   f(1) = 1^2 - 2(1) - 8 = - 9.   vertex is at (1, -9).

        2(1) 

find another point on the curve:   let x=0, for which y=-8.   then (0, -8) is on the curve.   plot the vertex and this point and draw a smooth parabola thru both.

hope this