( X 10) + ( X 1) = 40 chewing-gums
( X 10) + ( X 1) = 10 chewing-gums
( X 10) + ( X 1) = 32 chewing-gums
( X 10) + ( X 1) = 28 chewing-gums
( X 10) + ( X 1) = 18 chewing-gums
( X 10) + ( X 1) = 8 chewing-gums