pleass state the formulas used using decreasing annuity formula

10. Francesca will make annual deposits for the next thirty years, into a savings account paying an annual effective rate of 5.2%. Her first deposit is for $5000 and is made today. In one year, she will deposit $4900 and one year after that she deposits $4800. Each year after that she deposits $100 less than the previous year. * For each of the following, write an expression using actuarial symbols, write the formulas corresponding to the symbols, and then evaluate: (a) Compute the value in the fund immediately before her 4th deposit. (b) Compute the value in the fund immediately before her 20th deposit. (c) Compute the value in the fund immediately after her 12th deposit