Montgomery County Schools will tighten their budgetary belts, particularly if the TRM proposal is adopted this fall, according to Kenneth Muir. director of information for the school system.

Muir discussed the question. "Can Montgomery still afford a good school system" at a meeting this week of the Suburban Area Study Group, a citizen organization that explores topics in public education.

"The answer depends on our priorities," said Muir, who added that if the voters priority is a TRIM tax cut, the school system could face a $25 million reduction in services.

The TRIM proposal, question E on the Nov. 7 general election ballot, would reduce the county's general property tax rate from $2.60 per $100 of accessed value to $2.25.

To illustrate the effect a TRIM tax cut would have on the school system. Muir presented a chart that detailed possible cutbacks. According to the sample cutbacks, almost half of the reduction would come from a wage freeze that would mean to cost-of-living or step increases for school employes, 400 of whom would be laid off. Increasing the average class size by one pupil, eliminating new furniture and equipment purchases, reducing the instructional materials by 10 percent and reducing the clerical, custodial and teacher aide staff by 10 percent are some of the cutbacks the schools could face.

On the administrative level, the sample chart provided for elimination of one area administrative office, elimination of 70 central office administrative and instructional support positions and elimination of 35 maintenance, supply and other systemwide support positions.

"Even if there were no ballot questions, the picture still doesn't look too bright," said Muir, noting that inflation has risen faster than the school budget. For fiscal 1979, the budget is $268.5 million, which represents about half of the county's total budget.

The school system currently spends about 85 percent of its budget for salaries and fringe benefits of its almost 12,000 employes. Eightly percent of the employers work in the schools in positions such as principals, teachers, hall monitors and business administrators.

While the total enrollment is declining, enrollment in the more expensive continuum education programs has increased. Muir said, Continuum education includes such area as gifted and talented programs and special education for the physically and mentally handicapped.

In the last three years, enrollment dropped from about 117,000 to 108,000, resulting in the elimination of 782 positions from the schools. Enrollment in continuum education, however, has increased by 19 percent, creating 250 staff positions.

Educating a child in regular school programs costs $2,200 to $2,400 a year, while the continuum education programs cost $2,500 to $5,000, according to Muir.