17 < 9 + x Subtract 9 from both sides.
17 - 9 < 9 - 9 + x
8 < x
Be very careful that you leave the open end of the less than symbol pointing towards the x It means that x is greater than 8.
You could write it the other way x > 8 but the pointy end must always be closest to the 7 which is another way of saying what the answer means.
Notice anything after the 8 going right is colored and it is the answer.