Let "a", "b" and "c" be the numbers of cookies that A, B and C had originally.


The first equation is


    a + b + c = 181.    (1)


After all events, A had  0.8a cookies,  B had (b+28)  and C had 4c cookies.


We are given this long proportion  0.8a : (b+28) : 4c = 2 : 5 : 8.


It means that

    0.8a = 2x,

    b+28 = 5x

    4c = 8x

for some unknown number x.


From these equations,  


    a = ,             (2)

    b = 5x - 28           (3)

    c = 2x.               (4)


Substitute it into equation (1). You will get


     + (5x-28) + 2x = 181.


Now solve this equation and find "x".


Then find "a", "b" and "c" from (2), (3) and (4).


Check if your answer are INTEGER numbers.