Prove that if H and K are subgroups of a group G, then is a subgroupof G.

BUSINESS RULES Each SALES_REP has a COMMCLASS Each COMMON CLASS sometimes has a SALES_REP Each SALES_REP belongs to a DEPARTMENT Each DEPARTMENT sometimes has one or more SALES_REP Each SALES_REP can have many TRANSACTIONS Each TRANSACTION can only have one SALES_REP Each TRANSACTION belongs to one CUSTOMER...