How many miligrams are equal to 8 grams

Which exponential function has an initial value of 2? f(x) = 2(3x) f(x) = 3(2x)

With number 11 ( show how you got the answer)

Abicycle training wheel has a radius of 3 inches. the bicycle wheel has a radius of 10 inches.approximately how much smaller, in square inches and rounded to the nearest hundredth, is the area of the training wheel than the area of the regular wheel? *