a) Ta có:   $16 = 2^{4}   ;  24 = 2^{3}.3$

=> ƯCLN(16, 24) = $2^{3} = 8$

=> Ư(8) = {1, 2, 4, 8}.

Vậy ƯC(16, 24) = {1, 2, 4, 8}.

b) Ta có:  $180 = 2^{2}.3^{2}.5 ;  234 = 2.3^{2}.13$

=> ƯCLN(180, 234) = $2.3^{2} = 18$

=> Ư(18) = {1, 2, 6, 9, 18}.

Vậy ƯC(180, 234) = {1, 2, 6, 9, 18}.

c) Ta có:   $60 = 2^{2}.3.5 ;   90 = 2.3^{2}.5  ;  135 = 3^{3}.5$

=> ƯCLN(60, 90, 135) = 3.5 = 15

=> Ư(15) ={ 1, 3, 5, 15 }.

Vậy ƯC(60, 90, 135) = {1, 3, 5, 15}.