I need some help math

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

Which type of graph would allow us to compare the median number of teeth for mammals and reptiles easily

Problem number 26 of the rhind papyrus says: find a quantity such that when it is added to of itself the result is a 15. the modern day equation that models this problem is x + x = 15. what is the solution to the equation? x = 10 x = 12 x = 15 x = 30