How would you rewrite the query to ensure that the index you created in Problem $31$ is used?

SELECT

CUS$\_$CODE, MAX$($LINE$\_$UNITS$*$LINE$\_$PRICE$)$

FROM

CUSTOMER NATURAL JOIN INVOICE NATURAL JOIN LINE

WHERE

CUS$\_$AREACODE $=\text{'}615\text{'}$

GROUP BY

CUS$\_$CODE;