Answer:
part 6: -4x^3(2x^2 - 9x^2)
= -4x^3(-7x^2)
= -4*-7 (x^3+2)
= 28 x^5
part 7: 5t^-2* 2t^-5
= 5* 2 (t^-2-5)
= 10 t^-7
part 8: (3x)^4
= 3*3*3 x^4+4+4
= 27 x^12
part 9: (6m^4)^2
= 6*6 m^4+4
= 36 m^8
part 10: (x^2)^5 (x^3)^-2
= x^2+2+2+2+2 * 1/x ^3+3
= x^10/x^6
= x^10-6
= x^4
part 11: (3b^-2)^2 * (a^2*b^4)^3
= ((3*3)/b^-2-2) * a^2+2+2 * b^4+4+4
= 9/b^-4 * a^6/b^12
= 9 a^6 b^12-4
= 9 a^6 b^8
part 12: (2a^2b^5)^-4* (b^-2a^8)^6
= (1/2*2*2*2 a^2+2+2+2 2*2*2*2 b^5+5+5+5) (1/b^2+2+2+2+2+2 * a^8+8+8+8+8+8)
= (1/256 a^8 b^20)(1/b^12 * a^48)
= (1/256 a^48-8 b^-12-20)
= 1/256 a^40 b^-32
Part 13: 10^9/10^3
= 10 ^ 9-3
= 10 ^ 6
= 1,000,000
Part 14: 4m^10/2m^8
= 4/2 m^10 - 8
= 2 m^2
Part 15: y^3z^10/y^5z^9
= y^3-5 z^10-9
= y^-2 z
= z/y^2
Part 16: a^8b^6c^7/a^4b^10c^3
= a^8-4 b^6-10 c^7-3
= a^4 b^-4 c^4
=a^4 c^4/ b^4
Part 17: d^2 e^3 f^5/e^6 f^7 g^9
= d^2 e^3-6 f^5-7 g^-9
= d^2 e^-3 f^-2 g^-9
= d^2/e^3 f^2 g^9
Part 18: m^-3/3m^-6
= 1/3 (m ^ -3-6)
= 1/3 m^ -9
i hope it will help you!