Below are the business rules that define relationships between entities INVOICE, SALESREP,

CUSTOMER, PRODUCT, LINE, VENDOR.

$1)$ An INVOICE is written by a SALESREP.

Each sales representative $($SALESREP$)$ can write many invoices, but each invoice is

written by a single sales representative $($SALESREP$).$

$2)$ Each INVOICE is written for a single CUSTOMER. However, each CUSTOMER can have

many invoices.

$3)$ An INVOICE can include many detail lines $($LINE$).$ Each invoice line item can only

contain one and only one INVOICE

$4)$ Each PRODUCT can include many detail lines $($LINE$).$ Each invoice line item can

only contain one and only one PRODUCT

$5)$ A VENDOR may supply zero or more products, but a PRODUCT may be supplied by one

and only one VENDOR.

$6)$ The product information is stored in a PRODUCT entity.

$7)$ The product$$s vendor information is found in a VENDOR entity.

INVOICE entity: INV$\_$NUM $($PK$),$ INV$\_$SUBTOTAL, INV$\_$TAX, INV$\_$TOTAL

SALESREP entity: SLSREP$\_$NUM $($PK$),$ SLSREP$\_$LNAME, SLSREP$\_$FNAME, SLSREP$\_$INITIAL,

SLSREP$\_$EMAIL

CUSTOMER entity: CUST$\_$NUM $($PK$),$ CUST$\_$LNAME, CUST$\_$FNAME, CUST$\_$AREACODE,

CUST$\_$PHONE, CUST$\_$EMAIL, CUST$\_$ADDRESS, CUST$\_$CITY, CUST$\_$STATE, CUST$\_$ZIP$\_$CODE

INV$\_$LINE entity: INV$\_$LINE$\_$NUM $($PK$),$ INV$\_$LINE$\_$PRICE, INV$\_$LINE$\_$QUANT, INV$\_$LINE$\_$TOTAL

VENDOR entity: VEND$\_$CODE$($PK$),$ VEND$\_$NAME, VEND$\_$CONTACT, VEND$\_$EMAIL

PRODUCT entity: PROD$\_$CODE$($PK$),$ PROD$\_$PRICE, PROD$\_$DESCRIPTION, PROD$\_$QOH

What are the primary keys and foreign keys for this?