On a highway a wreck occurred and caused a 15 mile traffic jam on one side of the road. The average car is 12.5 feet in length, the average truck is 30 feet in length, and the average 18
wheeler tractor trailer is 75 feet in length. 60% of the traffic jam consists of cars, 25% trucks,
and 15% 18 wheeler tractor trailers. If the average distance between vehicles is 3.5 feet, how
many vehicles are stuck in the traffic jam?

if the eqn of the parabola is f(x) = (x-4)(x+2), we need to mult. this out to find the coordinates of the vertex.

then f(x) = x^2 + 2x - 4x - 8, and f(x) = x^2 - 2x - 8.

one way in which you can find the vertex is to calculate x = -b / (2a).   here, that comes to

        )

x = = 1.   f(1) = 1^2 - 2(1) - 8 = - 9.   vertex is at (1, -9).

        2(1) 

find another point on the curve:   let x=0, for which y=-8.   then (0, -8) is on the curve.   plot the vertex and this point and draw a smooth parabola thru both.

hope this

b. 153 students do not participate in sports and seventy-five 12th graders were surveyed