SOLUTION: A sum of 8550 is to be paid in 15 installments where each installment is 10'more than the previous installments. Find the first installment and the last installment.

Question 714731: A sum of 8550
is to be paid in 15 installments where each installment is 10'more than the previous installments. Find the first installment and the last installment.
Answer by DrBeeee(684) (Show Source): You can put this solution on YOUR website!
Let x = the first payment.
The sequence of 15 payments is
(1) x, x+10, x+20, x+30, ... , x+140
The sum of these 15 payments is
(2) 15x + 10*(14*15/2) or
(3) 15x + 1050
Now set (3) equal to the total sum to be made and get
(4) 15x + 1050 = 8550 or
(5) 15x = 7500 or
(6) x = 500
The last payment in (1) is x + 140 or
(7) 15th = 640
Answer: The first payment is $500 and the last payment is $640.
I'll leave it to you to add up the sequence of (1) to "prove" that our answer is right. LOL

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