10 classrooms
With 2 left over.
It's a simple question, make sure that you know that the key is 32/3, and because it's not fully divisible use the whole number (10)
keeping in mind that perpendicular lines have negative reciprocal slopes, let's check for the slope of the equation above

well then therefore

so we're really looking for the equation of a line with slope of -1/3 and that passes through (1, -3 )
