A+b+c = 131
b = 7 + 2a and c = a - 12
so a + 7+2a + a-12 = 131
then 4a -5 = 131
then 4a = 136
and a = 34....so b= 75 and c = 22....check 34+75+22=131√
3:1 ratio meaning for every 3 brown eyed people there are 1 blue eyed. So if you have 12 brown every you have 4 blue eyed. Giving you a total of 16 people.
This would be 3990 if you require a whole number but for a decimal it would be 3989.24