From the graph: there are 200 students overall. For the next 100, we can divide each number by 2 to find an estimate for how many with participate in MATH tutoring. 40 divided by 2 =20 students participating in MATH tutoring.
Part B- There are currently 55 students out of 200 in SCIENCE tutoring. We add 55 more for 400 = 110, add 55 more for 600=165, and then add half of 55 (27.5 or 28 because you CANNOT have half a student) for 700 students total. 55+55+55+28=193 students.
