BLACKSBURG — Josh Jackson threw for a touchdown and ran for another on Saturday night to lead No. 13 Virginia Tech to a 24-3 win over Duke. Jackson hit Sean Savoy with a 26-yard pass just before halftime to give the Hokies (7-1, 3-1 Atlantic Coast Conference) a 17-3 lead. He scored on a 6-yard run in the third quarter, all but cementing Virginia Tech’s third victory in a row on a night when it rained for most of the second half and footing became increasingly uncertain. The Blue Devils (4-5, 1-5) lost their fifth in a row.