Select the number that can replace the question mark (?) in the following series.
15, 30, 44, 57, 69, ?
In each term from the left end 15, 14, 13, 12, and 11 will be added to get the next one.
15+15 =Â 30
30+14 =Â 44
44+13 = 57
57+12 = 69
69+11 = 80
Hence 80 will come in place of the question mark.
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