Answer:
Step-by-step explanation:
(5x)^3 ⋅ (3/10)x^(-5) = 5^3⋅x^3 ⋅ (3/(2⋅5)x^(-5)
= 5^(3-1)x^(3-5)(3/2)
= 5^2x^(-2)(3/2)
= (75/2)x^(-2)