The answer 300 seconds/5 minutes
A and C are the correct answers.
Answer:
The first term is:
Step-by-step explanation:
The arithmetic sequence is defined by

where
is the first term
is the common difference
as
the 17th term of an arithmetic sequence is 51.
i.e. 
so

∵
,
, 
∵ 

Therefore, the first term is:
Yes because it goes up and back down