Please help me with these problems

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?

Two corresponding sides of two similar triangles are 3cm and 5cm. the area of the first triangle is 12cm^2. what is the area of the second triangle?

The weight v of an object on venus varies directly with its weight e on earth. a person weighing 120 lb on earth would weigh 106 lb on venus. how much would a person weighing 150 lb on earth weigh on venus?