Don't know if it's right, but do let me know! use percentage to visualise your workings. :)
(m-21) (m+1)there I thinks it's right unless I messed up my work
Answer:
The sum of the first 880 terms in the sequence is 2,273,920.
Step-by-step explanation:
Arithmetic sequence:
The difference between consecutive terms is always the same, called common difference, and the nth term is given by:

In which d is the common difference.
Sum of the first n terms:
The sum of the first n terms of an arithmetic sequence is given by:

ai = ai-1 + 6
This means that 
In this question:
Sum of the first 800 terms, so 
First term is -53, so 
The 880th term is:

Sum

The sum of the first 880 terms in the sequence is 2,273,920.
2,2 is 3,4 away from 5,6 and 3²+4²=25=5² so CD=5
The answer is 30 feet per hour
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