100^1/3 * 2^8/6 * 1/5^5/3 = (5^2*2^2)^(1/3) *2^(4/3)*5(-5/3) = 5^(2/3)*2^(2/3)*2^(4/3)*5(-5/3) = 

=5^(2/3-5/3)*2^(2/3+4/3) = 5^(-3/3)*2^(6/3) =5^(-1)*2^2 =4/5 =0,8