Hello, I am reposting with correct ASCII format with my answer:
(4x^5y^6z)2^ X (5x^9y^12z)3^
(16x^7y^8z^2) X (125x^12y^15z3^)
2000x^19y^23z^5
Thank you
(x^a)^b = x^(ab)
x^a * x^b = x^(ab)
So,
(4x^5y^6z)^2 * (5x^9y^12z)^3
= 16x^10y^12z^2 * 125x^27y^36z^3
= 2000 x^37 y^48 z^5
(x^5)^2 = (x^5)(x^5) = x^10, not x^7