All 231 students in the math club went on a field trip. Some students rode in vans which hold 7 students each and some students rode in buses which hold 25 students each. How many off each type of vehicle did they use if there were 15 vehicles total
We have this system :
V + B = 15 ⇒ V = 15 - B (1)
7V + 25B = 231 (2)
Sub (1) into (2) for V and we have that
7 (15 - B) + 25B = 231 simplify
105 - 7B + 25B = 231
105 +18B = 231 subtract 105 from each side
18B = 126 divide both sides by 18
B = 7 (buses)
V =15 - 7 = 8 (vans)