The League of Women Voters of Lexington will host a forum Friday about the state budget and how it affects the town. Luc Schuster, a senior policy analyst with the Massachusetts Budget and Policy Center, will talk about how past tax policy choices have contributed to the state’s fiscal crisis and led to painful cuts to many programs. He will also outline how the decisions affected programs designed to support cities and towns, including education funding. Three local Democrats, state Senators Michael Barrett of Lexington and Ken Donnelly of Arlington, and state Representative Jay Kaufman of Lexington, will also discuss ways the state could improve its revenue system. The free forum, part of monthly series hosted by the local League of Women Voters chapter, will be held in the community meeting room on the lower level of Cary Memorial Library beginning at 9:30 a.m.