Please help!

Create a function that accepts four user inputs: (1) a cash flow amount; (2) a discount rate; (3) the number of periods; and (4) an indicator for which TVM calculation to compute (we call this the 'operation'). Name the function "Calc_TVM' If the argument (cperation) supplied by the user in cell B20 is the letter "p", then the function should compute and return the Present Value of the lump sum cash flow amount. If the argument (operation) supplied by the user in cell 8.20 is the letter "F", then the function should compute and return the Future Value of the lump sum cash flow amount. If the argument (operation) supplied by the user in cell B20 any value OTHER THAN a "P" or "F" then the function should return the numeric value 999. NOTE: functions return walues to the cell from which they are calied. I have include numeric data for use in celis B17:B19 - call the Calc_TVM function from cell C22 Enter the letter ' p ' to find the present value of the lump sum cash flow, enter the let Call the Calc_TVM function here: * Yourfunction should cantain NO Celis ar Range commands w. ensure you pass in the dofa as arguments within the function li " Your function shouid contoin a nested if structure