Answers

2016-07-24T14:27:36+08:00
Summation of sequence (530) = (1/2) (number of terms) (first term + last term) 

When the first term is = x, using the equation above
530 = (1/2) (10)(x + 80) 
x = 26 

For the common difference
80 = 26 + d(10-1) 
d = 6
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