Which of the following is a parent function?

What's the difference between: x≥0 and nonnegative integer. ?

Julius sold five times as many computers as sam sold last year. in total, they sold 78 computers. how many computers did julius sell?

The figures below are made out of circles, semicircles, quarter circles, and a square. find the area and the perimeter of each figure and give your answers as a completely simplified exact value in terms of π (no approximations).