应该是求100^(2a-b/3)吧
100^(2a-b/3)
=100^2a÷100^(b/3)
=(10^a)^4÷（10^b)^(2/3)
=16÷3^(2/3)
=16×{[3^(1/3)]/3｝
=3分之16倍的3次根号3