What makes things concurrent?

What kinds of numbers make up the set of numbers called the real numbers? give examples when you explain a number type. there are a limited set of types of numbers, but an unlimited number of examples of these numbers.

Given the equation f(x)=a(b)x where the initial value is 40 and the growth rate is 20% what is f(4)

If f(x) = 6x – 4, what is f(x) when x = 8? a2 b16 c44 d52