Simplify the following, leaving your answers in index form: 4^{3} \times 4^{5} \div 4^{2} 9^{-4} \times 9^{5} \times 9^{-3} (1 / 3)^{3} \times(1 / 3)^{5} 2^{-4} \div 2^{-7}