(3/7а^2b)^6×(-(49/9ab^2)^3)
-(3/7)^6×a^12b^6×(49/9)^3×a^3b^6
-3^6/7^6×a^12b^6×7^6/3^6×a^3b^6
-a^12b^6a^3b^6
-a^15b^12
