See attached excel file, good luck. Note: the paramater at the end of the Pmt function is set to 1 so that it automatically treats it as an annuity due, and hence why the step of dividing the payment by (1+rate) isn’t done explicitly in the spreadsheet. When doing the lease problems by hand, you still have to do it like I showed you (unless you put your calculator in begin mode), and divide the payment by (1+after-tax rate). The answer for the BE lease rate will match the output from the spreadsheet at the end if you did it right, and that’s what matters.