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

1 Answer

Answer:

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

Explanation:

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)