The sum of 30 terms of an A.P where last term is 98, is 1635 . find its first term and the common difference.
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S30=30/2(a+l)
1635=15(a+98)
1635=15a+1470
1635-1470=15a
165/15=a
a=11
tn=a+(n-1)d
t30=11+(29)d
98=11+29d
d=3
1635=15(a+98)
1635=15a+1470
1635-1470=15a
165/15=a
a=11
tn=a+(n-1)d
t30=11+(29)d
98=11+29d
d=3
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