We have: a = 4c (1) b-c=164 (2). a+b+c=656 (3)
from (2) we get b=164+c replacing to (3) the values of a and b we get: 4c+164+c+c = 656
6c=656-164=492 ---->>> c=492/6 = 82 sustituting the value of c=82 to (1) we get a=4*82=328
so working on (1) we have 328+b+82=656 -->>> b = 656-328-82 = 246
testing the values we get: 328 = 4*82 = 328 b-c = 246-82 = 164