College Algebra problem PLEASE SHOW ALL WORK DO NOT skip or

College Algebra problem. PLEASE SHOW ALL WORK (DO NOT skip or combine steps and please explain what you\'re doing). I know the answer (it\'s provided with the question). I don\'t know how to solve the problem to arrive at that answer so I need to see ALL of the steps for arriving at the answer provided. Please TYPE your answers. I have a very hard time reading handwriting, especially if it\'s been scanned into the computer.

15. Find the arithmetic sum 4 9 14 999 ANSWER: 100,300

Solution

S = 4 +9 +14 ..... 9999

Its an Arithmetic progression with common differenc = 5

So, last term = 999

nth term of A.P. = a1 + (n-1)d

999 = 4 +(n-1)5

995 = (n-1)5

n -1 = 199

n = 200

So, sum of the series = n(a1+an)/2 = 200(4 +999)/2 = 100300