Which value is an output of the function?

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

In the diagram, ab is tangent to c, ab = 4 inches, and ad = 2 inches. find the radius of the circle.

Dylan is evaluation the expression 13+19+7+10 at one step in his work, dylan rewrites the equation as 13+7+19+10 which property of addition must dylan have used when he evaluated the expression?