If the 8% is per year, we need to calculate the acquired value after 20 years with compound interest. Formula : AV : aquired value after 20 years V : starting value r : rate y : years AV = V x (1+r)^y AV = 10 000 x (1+0.08)^20 AV = 10 000 x 4.660957 AV = 46 609.57 She will have available 46 609.57 $ after 20 years with compound interest if she save 10 000$.