Answer:
6 * s^(5t + 4t^2)
Explanation:
There are two expressions here that contain the base s: s^5t and s^4t^2. As part of the simplification process, we multiply these together (which involves adding the exponents):
s^5t * s^4t^2 = s^(5t + 4t^2)
Then 6s^5t x S^4t2 becomes 6 * s^(5t + 4t^2)