How would I find the formula for these problems? Please help me.. I would really appreciate it.. thank you

Calculate the present value of the following:
$7,000 in 5 years at an annual discount rate of 6%

$7,000 in 5 years at a semiannual discount rate of 6%

$7,000 in 5 years at a quarterly discount rate of 6%

$7,000 in 6 years at an annual discount rate of 6%