Ravens

The tale of the Seven Ravens were seven brothers, each of whom was born exactly 2.5 years after the previous one. When the eldest of the brothers was 2-times older than the youngest, mother all curse. How old was seven ravens brothers when their mother cursed?

Result

k1 (youngest) =  15
k2 =  17.5
k3 =  20
k4 =  22.5
k5 =  25
k6 =  27.5
k7 (oldest) =  30

Solution:

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