[ Mathematics ] Open Question : MATH HELP PLEASE!!! thank you :)?

simplify into simplest radical form: 1. x^-2y^-1/a^-1b^-3x 2. (4w^3x^5y^4)^4 3. (2r^-1)^4 (4r^2)^-2 4. (-3n^-3)^2/-9n^4 5. √200 6. 3√-64 7. -4√7 - 2√4 +4√63 8. √60 x √90