(x^7 y^4)^3 / (x^10 y^5)^2 = x^21 y^12 / x^20 y^10 = x^(21-20) y^(12-10) = x y^2
(3a^9 b^3)^2 : (-4a^4 b)^4 = 9a^18 b^6 : 256a^16 b^4 = 9/256(a^18/a^16)(b^6/b^4) = 9/256 a^2 b^2 = 9a^2 b^2
(7^2)^8 (6^3)^4 / (7^4 6^3)^4 = 49^8 216^4 / 2401 216^4 = 576480100000 * 19448199360 / 12091650880 = 1125899906842624000000000 / 12091650880 = 93000000000 = 1
(9^4 8^3)^5 / (9^10)^2 / (8^2)^7 = (6561 512)^5 / 3486784401 / 64^7 = 33592320000 / 3486784401 / 68719476736 = 33592320000 / 533123400000 = 63 = 8
(x^7 y^4)^3 / (x^10 y^5)^2 = x^21 y^12 / x^20 y^10 = x^(21-20) y^(12-10) = x y^2
(3a^9 b^3)^2 : (-4a^4 b)^4 = 9a^18 b^6 : 256a^16 b^4 = 9/256(a^18/a^16)(b^6/b^4) = 9/256 a^2 b^2 = 9a^2 b^2
(7^2)^8 (6^3)^4 / (7^4 6^3)^4 = 49^8 216^4 / 2401 216^4 = 576480100000 * 19448199360 / 12091650880 = 1125899906842624000000000 / 12091650880 = 93000000000 = 1
(9^4 8^3)^5 / (9^10)^2 / (8^2)^7 = (6561 512)^5 / 3486784401 / 64^7 = 33592320000 / 3486784401 / 68719476736 = 33592320000 / 533123400000 = 63 = 8