Well, to get annually, it is every year, so you would have to multiply the interest by 4(because 3 months times 4 is 12 months, and 12 months in a year)to get it yearly
75 x 4 = 300
Now divide 300 by 5,000
300/5000 = 3/50(divide each by 100)
Now multiply each by 2 to get a 100%, because it is ony at 50% right now
3 x 2 = 6, 50 x 2 = 100
6% is your answer, hope this helped!