Mr. Sandstrom's will directed that $20,000 be placed in each of two investment trusts for his grandchildren, Lena and Axel. On each grandchild's 18th birthday, he or she is to receive the first of a series of equal quarterly payments running for 15 years. Lena has just turned 13, and Axel's age is eight years, six months. If the funds earn 9.25% compounded semi-annually, what size of payment will each grandchild receive?