the sum of 5th and 9th terms of an ap is 72 cm and the sum of 7th and 12th terms is 97. find the a.p
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an=a+(n-1)d
Therefore
a+4d+a+8d=72
2a+12d=72----1
a+6d+a+11d=97
2a+17d=97----2
Solving 1 and 2
5d=25
d=5
2a+12(5)=72
2a=72-60
a=6
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