14. Batman and Superman both completed an obstacle course for their yearly physical. Batman completed 4 more than three times the number of obstacles that Superman completed. They completed a total of 24 obstacles. Which system of equations models this if Batman completed  obstacles and Superman completed  obstacles? 
A b + s = 24 B b + s = 24 
 b = 4s + 3 s = 3b + 4
C b + s = 24 D b + s = 24
 b = 3s + 4 s = 4b + 3