Answer:
(5x²y⁴z/2x^5z³)
Explanation:
That's a wacky looking multiplication! All you really need to do here is multiply straight across as you usually would; reducing terms and combining like terms where applicable.
(4x²y³z/9)•(45y/8x^5z³)=
(4•45•x²y⁴z/9•8x^5z³)= (<-- I reduce here)
(5•x²y⁴z/2x^5z³)=
(5x²y⁴z/2x^5z³)
You could put the "x" into the denominator as well and combine those terms, but I don't really see a good reason to do so.