Jeanette loaned Jerry 300 at an interest rate of 10% a year. How much interest will Jenna get if Jerry gets paid Jenna after six months

The interest rate is 10% per year, so for six months, the interest rate is 10/2 = <<10/2=5>>5%.

The interest Jeanette can get after six months is 300 * 5/100 = $<<300*5/100=15>>15. Answer: \boxed{15}.