Abacteria population triples in number each day . if there are 2,551,500 bacteria on the 7th day , how many bacteria were present on the first day ?

Well it is triples you can tell that it is a division question.  So triples means by 3. 
The equation is 2,551,500 = d X 3^6. So, now 2,511,500 / 729 is your final answer, 3,500. Hope it helps :)

A) early horses is your answer

Bc they get tired from playing with other kittens