Tim wants to save for retirement now. He will deposit $500 at the end of each month for 40 years (i.e. his first deposit will be in one month). He will earn 7% per year on his investments, compounded monthly. His sister Sarah does not want to save yet. She will wait 20 years before she deposits $1,200 at the end of each month, starting 20 years and one month from today. She will earn 12% per year, compounded monthly. Tim and Sarah will both retire at the same time in 40 years. What is the difference between their investments when they retire in 140 years