Answer:
10
Step-by-step explanation:
c)10
1) distribute 3 to (5^4)
5^2*5^k=5^12
divide by 5^2 on both sides
5^k=5^12/5^2
5^k=5^10
so k=10
we can recheck:
5^2*5^10=5^12
hope this helps
