EXPERT ANSWER
If uncle would have not loaned me, he would have deposited the money for these two years and earned interest on it that’s compounded annually. So, formulae of compound interest (CI):

(where P= Initial deposit, n= rate of interest, t=time period)
Following the above formulae:
CI = 20000[1+8/100]2 = 20000 x (1.08) x (1.08) = $23328
Final Amount = $23328
So, to make payment back of this final amount in every 6 months for 2 years, I would make 2 x 12/6 = 4 time installment payments.
So, payment in every 6 months = 23328/4 = $5832
ANSWER= PAYMENT OF $5832 IN EVERY SINGLE MONTHS TO BE DONE 4 TIMES.