The sequence a1, a2, a3, a4. a5 is such that an = a n-1 +5 for 2≤ n ≤ 5. If a5 = 35 what is the value of a1 ?	Choose the correct choice from the following answers:
A) 1
B) 6
C) 15
D) 16
E) 21
Here, each value of an is the previous value plus 5   Since the numbers are less, the fastest way to solve this problem is to successively subtract 5 from a5 till you reach a1   a5 = 35   a4 = 30   a3 = 25   a2 = 20   a1 = 15 &lt;&lt;&lt;&lt; Ans 15
<result>C</result>
The sequence a1, a2, a3, a4. a5 is such that an = a n-1 +5 for 2≤ n ≤ 5. If a5 = 35 what is the value of a1 ?