A new elementary school will have 50 faculty members. Some will be teachers and the rest will be aides. At this school, teachers will earn 20,000 dollars a year and the aides 12,000 dollars. The total amount to be spent on salaries is $872, 000. How many aides may they hire?

Answer 1

suppressing the useless thousands, we have

12a + 20(50-a) = 872