The measure of an angle is twice the measure of its supplement. How many angles are there? What is their relationship? How can you use algebra, such as the variable x, to help you?

So then the next question is: The measure of an angle is 20 less than its complement. We are supposed to find how many angle there are, what their relationship is, and how you can use algebra, such as the variable x, to help you. so for this one would it be x + 2x=90 ?