Hello there! The answer is B. (3, 21).
So you want to be able to substitute one of the equations into the other. We can't do this right now since both of the equations are y = something, so we need to change the second equation to x = something so we can plug it in to the value of x in the first equation.
y = x + 18 can translate to x = y - 18. Now, plug "y - 18" into x in the first equation.
y = 10(y-18) - 9 and solve.
y = 10y - 180 - 9
-9y = - 180 - 9
-9y = -189
y = 21.
Now we have our y value, but we need our x value. Well, remember that y = x + 18? So, since y is 21, what plus 18 is equal to 21? The answer is 3, making our x value 3.
If x = 3 and y = 21, the ordered pair is (3, 21) or option B. I hope this was helpful and have a great day! :)
