What was Melinda Gates' academic major and degree when she studied at Duke University?
SELECT ?value1 ?value2 WHERE { wd:Q463877 p:P69 ?s . ?s ps:P69 wd:Q168751 . ?s pq:P812 ?value1 . ?s pq:P512 ?value2 }
melinda gates: Q463877 duke university: Q168751