Given: x + y = 15.

which of the following are ordered pairs of this equation?

a.{(-3, , , 16)}
b.{(-3, , , 14)}
c.{(16, -, , 3)}

What you do is: PLUG IT IN!! (children clapping).

Lets plug in -3. When we plug in -3 for x, we would need to add it to 15. So that means

-3+y=15
y=18.

It shows that the ordered pair is actually (-3,18). So A and B are wrong. Now lets check out C. Lets plug in 16 for x and see what happens.

16+y=15
y=-1

Wow, it looks like the ordered pari for 16 would be (16,-1). So it looks like all your choices are wrong. Wow. But, from what I see, these ordered pair work:

(0,15)   (15,0)