How do you find an ordered pair for 3x - 4y = 18 and 5y = x - 28?

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Answer 1 · 2016-05-27T02:48:52

Solve for x in one equation in order to substitute it into the other equation and you'll work through to get (-2,-6)

Let's start with the original equations:

$3x-4y=18$
$5y=x-28$

We can solve the 2nd equation for x, then substitute that into the first equation. So let's first take the 2nd equation:

$5y=x-28$

and add 28 to both sides to get:

$x=5y+28$

We can now substitute that into the first equation:

$3x-4y=18$

$3(5y+28)-4y=18$

now let's solve for y:

$15y+84-4y=18$

$11y=-66$

$y=-6$

We can now substitute in the y value into one of our equations to find the x value. I'm going to use

$x=5y+28$

$x=5(-6)+28$

$x=-2$

Now let's check the answer:

$3x-4y=18$

$3(-2)-4(-6)=18$

$-6+24=18$ check!

$5y=x-28$

$5(-6)=(-2)-28$

$-30=-2-28$ check!

So the final answer is (-2,-6)