When you find the factors of something like this, you have to just get the letter alone.
For example: y-3. You have to first write it as y-3=0, then you add 3 from BOTH sides of the = so that you can make the -3 go away and y will be alone. So, it will look like this: y-3+3=0+3. Then, you solve it for y (which just means that you want y by itself on one side of the = ). So, -3+3=0, which means they disappear from that side; since 0+3=3, that's what that side turns into, so what you end up with is y=3
Same thing goes for the x+7 equation: x+7=0 x+7-7=0-7 x=-7
