Evaluate $5^{-3}$5−3 .
Evaluate $8^0\div4^{-3}$80÷4−3 without the use of a calculator.
Evaluate $5\times4^{-2}+9^0$5×4−2+90 without the use of a calculator.
Evaluate $3^{-4}+3^{-1}$3−4+3−1 by using exponent laws, giving your answer as a simplified fraction.