The equation for slope intercept form is y = mx + b, where m is the slope and b is the y intercept.
We can first find the slope. Perpendicular lines have slopes which are negative reciprocals of each other. This means that the slope of the line you're looking for would be the negative reciprocal of -2/9. The negative reciprocal of -2/9 is 9/2. Therefore, m = 9/2.
Substitute this into the equation. y = 9/2x + b. Now substitute in the point given and solve for b.
This means 35% used buses. 3+4=7, so 20% took school buses while 15% took public buses. 65%-35%=30% who mean the difference, so 30% is 360. You ask what is 15% -- that's half of that difference, or 180.
