An investor took out a loan of 150,000 at 8% compounded quarterly, to be repaid over 10 years with quarterly payments of 5,483.36 at the end of each quarter. After 12 payments, the interest rate dropped to 6% compounded quarterly. The new quarterly payment dropped to 5,134.62. After 20 payments in total, the interest rate on the loan increased to 7% compounded quarterly. The investor decided to make an additional payment of

X at the time of his 20

th payment. After the additional payment was made, the new quarterly payment was calculated to be 4,265.73 payable for 5 more years. Determine

X.