PULLMAN — Anu Solomon threw five touchdown passes and No. 15 Arizona beat Washington State 59-37 on Saturday in a game featuring the top offenses in the Pac-12.The freshman quarterback was 26 of 38 for 294 yards without an interception. Terris Jones-Grigsby added 107 yards rushing for Arizona (6-1, 3-1), which was coming off an off week after losing to Southern California.Washington State (2-6, 1-4), also off last week, lost its third straight game.Washington State’s Connor Halliday, the nation’s leading passer, completed 56 of 79 passes for 489 yards, with four touchdowns and two interceptions, and became the leading career passer in school history. Isiah Myers caught two touchdown passes for the Cougars.Washington State gave up 60 points in a loss to California and 59 points to Arizona in its past two home games.Arizona scored 24 straight points in the first quarter, including two touchdowns by DaVonte Neal, to win for the fourth consecutive time in Martin Stadium.Washington State went three-and-out on its first possession and punted. Neal returned the punt 81 yards for a touchdown, continuing a season-long trend of special-team failures for the Cougars. Arizona drove 84 yards on its next possession, but had to settle for Casey Skowron’s 31-yard field goal and a 10-0 lead.