I-ready math pls help

Barbara deposited $300 in the bank. if the bank pays her simple interest at the rate of 4 percent per year, how much money will she have in her account at the end of 9 months?

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? *

Suppose that 15 inches of wire cost 60 cents. at the same rate, how much (in cents) will 12 inches of wire cost