Because line AB is perpendicular to line BC, the slope of AB is equal to 3/2. Substituting (-2,1) into the new equation gives us "1=3/2(-2)+b" which simplifies to 1=-3+b. This means that b=4.
5/20 students in Alessandro's class live in Oakdale, which can be simplified to 1/4. 1/4 in decimal form is 0.25. Now to convert it to a percentage, you just multiply that by 100. So 25% of students in Alessandro's class live in Oakdale.