Montgomery County residents have long been proud of their award-winning public school system. But then came the shocking news that 61 percent of high school students flunked the final Algebra I exam, while only 11 percent earned an “A” or “B.” Similar high failure rates were posted in geometry (62 percent) and Algebra 2 (57 percent). And they were not limited to math: Between 37 percent and 50 percent also failed biology, English and history exams. Add the fact that nearly 70 percent of Montgomery County Public Schools graduates who attend Montgomery College need remedial help in math, and stunned parents and elected officials are openly wondering whether their school system’s glory days are behind it.