Question

What is being done to the variable in the equation y + 8.5 = 17.2?

Answer 1

You're solving for "y", aren't you?

If that's the case, then subtract 8.5 from both sides (8.5-8.5 & 17.2-8.5)
You should end up with "y= 8.7"

So, y= 8.7

Hope this helped!

Answer 2

The number 8.5 is being added.