<PRE><B>Question 1161389</B>
sum=an=4370. This equals (n/2)(2a1+(n-1)d). a1=50 and d=20
so multiplying by 2, and 8740=n(100+20n-20)
100n+20n^2-20n=8740
20n^2+80n-8740=0
n^2+4n-437=0
n=-4+/-sqrt(1764)/2
=(1/2)(-4+42), positive root only
=19 years ANSWER
divide everything by 10
5/7/9/11/13/15/17/19/21/23/25/27/29/31/33/35/37/39/41=437
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