The answer to your question is X= 11
Recall that the volume of a regular prism is given by the area of the base times the height.
Given that the base of the prism is a regular pentagon with an apothem of 2.8 centimeters.
The pentagon consist of 5 isosceles triangles with the apothem as the height and the side of the pentagon as the base.
Recall that the are of a triangle is given by 1/2 base times height.
Thus the area of of the pentagon base of the prism is given by

Therefore, the volume of the prism is given by
The percentage of walkers who got a ride is 37.5/3=12.5%
The number of that is 0.125*24=3 students.
The answer would be B. Using the foil method to check, the two k's equal k^2, then the k and -f would equal -fk, plus the 2fk would equal a positive fk. Lastly, the 2f and -f would equal -2f^2.