normally "present value" in krat speek meen the $ yu gotta put up
then ern interest for x yeers & then will be 20,000$
"semiannual" meen 2 times a yeer
for 10%, 2 times/yeer*6yeers... kompound interest=(1.05)^12=1.795856326
so yu gotta put up 20,000$/1.795856326
=11,136.75$