Arlington County Schools Superintendent Patrick K. Murphy unveiled a $539.4 million budget plan Thursday that would increase salaries and consolidate services for students pursuing alternative paths to high school graduation.

The plan, which represents a 3 percent increase over the current year’s spending, accounts for a projected 800-student boost in enrollment. It invests in new literacy efforts in the early years and a technology initiative to fund tablets for every second- and sixth-grader.

About $7 million would be devoted to a 2 percent cost of living increase for employees who serve the school system, which is projected to have 24,150 students next school year.

“I realize it’s a competitive market out there,” Murphy said in a news briefing. “We wouldn’t be having the results we have without a high-quality staff.”

Arlington County is a high-performing district that has some of the highest school spending in the Washington region. Murphy’s plan represents the fourth year of sustained per-student spending increases. If approved, spending for fiscal 2015 would be $19,244 per student, just slightly below pre-recession funding levels in 2009.

The plan also would cut 75 positions and $7.3 million from the budget, largely by eliminating library assistant positions and consolidating the Langston alternative high school program with Arlington Mill High School. The proposal also calls for changes to services provided for adult students who want to earn high school diplomas.

Murphy said the savings would not lead to layoffs, and staff would be able to find new jobs within the school system.

The county funds the vast majority of the budget — just over 80 percent. Budget work sessions begin Thursday night, and the first public hearing is scheduled for March 20. The School Board plans to adopt the final budget May 8.