How do you do a uniform motion math problem?

You give a $4 tip for a meal that cost $22. approximately what percent of the bill was your tip?

1- what do you think the product of a nonzero rational number and an irrational number is? is it rational or irrational? make use of variables, the closure property of integers, and possibly a proof by contradiction to prove your hypothesis.2- why do we have to specify that the rational number must be nonzero when we determine what the product of a nonzero rational number and an irrational number is? if the rational number were 0, would it give us the same result we found in the first question?

The circle below is centered at the point (3, 1) and has a radius of length 2. what is the equation?